With this lower placement of the Temple compound and also the placement of Fort Antonia on the Dome of the Rock platform the measurement all the way round is 6 furlongs just as Josephus said it was.

According to Josephus the Temple compound alone was 4 furlong around, that is aproxamatly 600 X 600,  but when Fort Antonia was included in the Temple complex, together it was s 6 furlong around.  So Fort Antonia was also a square of 600 X 600.
 
 

Herod had built the new temple by the Time of Jesus but the new walls of the extended compound were built by Herod's son, according to his fathers plans. The new walls were completed in 66 AD and so by the time of Josephus' visit to the Temple Mount it was completed and would have looked like the above drawing.  By 70 AD it had all been destroyed by Titus.

But Fort Antonia was not thought of as being seperate from the Temple compound. It was part of it.  Between the temple compound, which was square, and Fort Antonia, which was also square, the two formed a rectangel that was two furlong/stadium long on east and west and one furlong/stadium on north and south.

In a plea of Josephus to the Jews he quoted an old Jewish prophecy that said "When the Temple becomes four-square once again then will the temple and city be destroyed."  By the destruction of Fort Antonia the temple HAD once again become four-square and he begged them to make peace with the Roman's before it was to late. Of course they refused.

BOOK 6 :7. In the mean time, the rest of the Roman army had, in seven days' time, overthrown [some] foundations of the tower of Antonia, and had made a ready and broad way to the temple.

Then the Jews (the tyrants among them) set on fire the cloisters that conected Fort Antonia to the Temple compound on the northwest and north to sever the Temple from the Fort.  With this act the Temple was once again four-square.
 

2. How was the fort attached to the Temple compound?
Flavius Josephus in 93 C.E.
BOOK 5, CH. 5 Josephus Flavius regarding Tower of Antonia;
8. Now as to the tower of Antonia, it was situated at the corner of two cloisters of the court of the temple; of that on the west, and that on the north; it was erected upon a rock of fifty cubits in height(75 feet high), and was on a great precipice; (steep hill) it was the work of king Herod, wherein he demonstrated his natural magnanimity.

........but on the corner where it joined to the two cloisters of the temple, it had passages down to them both, through which the guard (for there always lay in this tower a Roman legion) went several ways among the cloisters, with their arms, on the Jewish festivals, in order to watch the people, that they might not there attempt to make any innovations;
See above map
Also see map as it would have been attached before Herod's extended walls Click Here

The dark blue line shows the size of the mount today. 
The Temple complex along with Fort Antonia was 2 furlong long and one furlong wide. 

3. Was there a low wall surrounding the Rock creating a platform?
Josephus continues: In the first place, the rock itself was covered over with smooth pieces of stone, from its foundation, both for ornament, and that any one who would either try to get up or to go down it might not be able to hold his feet upon it.

This would mean the sides of the 74 foot hill  was covered with smooth stones so that if anyone try to climb up to the fort they would slip on the smooth stone and not be able to get up the steep hill to the base of the Fort.

Josephus continues:Next to this, and before you come to the edifice of the tower itself, there was a wall three cubits high; (4.5 feet high) but within that wall all the space of the tower of Antonia itself was built upon, to the height of forty cubits (60 feet).

A 4.5 foot wall surrounded the upper part of the hill and the fort was built within that wall.  This would mean that land fill was placed within the bounders of this low wall to create a flat spot to build the Fort.
 
 

4. What were the dimensions?

Flavius Josephus BOOK 15 CHP 4,
4. Now on the north side was built a citadel, whose walls were square, and strong, and of extraordinary firmness. This citadel (Tower of Antonia) was built by the kings of the Asamonean race, who were also high priests before Herod, and they called it the Tower, in which were reposited the vestments of the high priest, which the high priest only put on at the time when he was to offer sacrifice.
...............But for the tower itself, when Herod the king of the Jews had fortified it more firmly than before, in order to secure and guard the temple, he gratified Antonius, who was his friend, and the Roman ruler, and then gave it the name of the Tower of Antonia.
 

(Josephus Flavius regarding Tower of Antonia, the height of the fortress and its towers.
Josephus continues speaking of Fort Antonia: The inward parts had the largeness and form of a palace, it being parted into all kinds of rooms and other conveniences, such as courts, and places for bathing, and broad spaces for camps; insomuch that, by having all conveniences that cities wanted, it might seem to be composed of several cities, but by its magnificence it seemed a palace. And as the entire structure resembled that of a tower, it contained also four other distinct towers at its four corners; whereof the others were but fifty cubits high; whereas that which lay upon the southeast corner was seventy cubits high, that from thence the whole temple might be viewed;

 
 
• The rock on which the fortress was built was 50 cubits high (74 feet) (We can assume he was measuring from Barkley gate which was street level in the Tyropoeon valley ,which is approxamatly 50 cubits lower than the rock inside the Dome.  Barkley gate 721.3 M (2366.4 feet) above sea level. Rock 743.7 M (2440.0 feet) above sea level)
• The height of the fortress itself was 40 cubits (60 feet)
• and it had 4 towers, one in each corner.
• The height of three of the towers was 50 cubits and the fourth (southeast corner) tower was 70 cubits (102 feet )
•  The Antonia Fortress was a military fortification and Josephus said that the whole Fortress of Antonia appeared as one tower.

5. What valley's were on the East and West of the fort?

 Josephus gave the details;
 
• The Fortress of Antonia was partly surrounded by a deep ravine 165 feet wide. (Kidron) (see map)
• The western wall was built upon the edge of the cliff overlooking the Tyropoeon Valley. (See map)

• The north wall was directly across from the hill Bezetha and there wasa deep mote between them. The rock hid the Temple from the  hill Bezetha. (see above map for location of that city at the top of the map)
• The southern wall of Fort Antonia one could see over the entire Temple area.
• The eastern wall overlooked the Pool of Bethesda and the Kidron Valley. (see map to see the the angle of the pool from the fort.)

 

The accepted location of the Fort places the Fort on the wrong side of the moat!

 2.   .................... It was Agrippa who encompassed the parts added to the old city with this wall, which had been all naked before; for as the city grew more populous, it gradually crept beyond its old limits, and those parts of it that stood northward of the temple, and joined that hill to the city, made it considerably larger, and occasioned that hill,which is in number the fourth, and is called "Bezetha," to be inhabited also.

It lies over against (across from) the tower Antonia, but is divided from it by a deep valley, which was dug on purpose, and that in order to hinder the foundations of the tower of Antonia from joining to this hill, and thereby affording an opportunity for getting to it with ease, and hindering the security that arose from its superior elevation; for which reason also that depth of the ditch (moat) made the elevation of the towers more remarkable. This new-built part of the city was called "Bezetha," in our language, which, if interpreted in the Grecian language, may be called "the New City."

Josephus, in his description of the siege of the Temple by Pompey, BC 63, says that the Roman
Commander found it impossible to attack it on any other quarter than the north, on account of the
frightful ravines on every other side; and that even on this side (north side) he had to fill up "the fosse (moat) and
"the whole of the ravine, which lay on the north quarter of the Temple;" and in the description of
the siege of the Temple by Herod, BC 38, 37, he says, that Herod made the attacks in the same
manner as did Pompey, that is, from the north side of it.

When he comes to the description of the siege by Titus, AD 70, the Temple with its enclosure,
and the tower of Antonia at the north-west angle of the enclosure, having been entirely rebuilt by
Herod, BC 17, Josephus says that the design of Titus was "to take the Temple at the tower of
Antonia;" and that for this purpose he raised great banks; one of which was at the tower of
Antonia, and the other at about 20 cubits from it; and that for the purpose of obtaining materials
for filling up the immense fosse and ravine to the north of the Temple, he had to bring them from
a great distance; and that the country all round for a distance of 19 or 12 miles was made
perfectly bare in consequence.

Here is a quote from the web page of by Lambert Dolphin and Michael Kollen

1. Where was the Antonia Fortress?

Ancient Jerusalem was protected on the east, south, and west by valleys. The Antonia Fortress was located to the north to protect the weaker north side of the city. (In fact, it was from the north that Titus Vespasian breached the walls in his famous attack in 70 C.E.)

According to ancient sources, the fortress was on a hill about 25 meters high. The current El Omriah school building is on a rock only 5 meters high. From many stratographic and other considerations it is doubted by some experts that this was the actual location of the Antonia Fortress. Tuvia Sagiv's papers discuss the critical issue of the actual location of the Fortress Antonia, which he believes was well to the south, perhaps at the location of the Dome of the Rock.

2. The Location of the Ancient North Moat (the Fosse)

Traditional renderings show a deep, filled-in fosse (moat), north of the Temple Mount, lying south of the Antonia Fortress, between the fortress and the Temple Mount.

According to ancient sources, however, the Antonia Fortress and the Temple Mount were adjacent to each other. The moat should be to the north of the Tower for protection, placing the Antonia about where the Dome of the Rock stands today!  End quote

The old wall of the City of David

Click on map to enlarge

Notice the tower of the hundred (Meah) is in the same place as the future Fort Antonia's northeast tower would be located.
And notice the Temple complex fits well within the city walls that Nehemiah rebuilt, as it should be.

The Tower of Sammeah {Meah=hundred).  Perhaps a 100 cubits high.  Located on the old North wall, called by archaeologists the Ancient North Wall. Nehemiah tells us that  Tower of Sam-meah was between the Sheep Gate and the Tower of Hananeel in the North Wall.

It is believed that Hezekiah (700B C) built the lower portions of the east wall all the way from the bend in the east wall to just beyond the east gate (some believe to be the Golden gate) at that point the wall had a corner and went westward across the Temple Mount.  When Herod built the outer walls (3rd city wall) He joined to the ezekiel wall to incase the whole area.  That upper section of the temple mount we see today was a moat and a valley that was filled in by Herod when he attacked Jerusalem from the north in 61 BC.  He built the 3rd city wall after 63 BC. 

Straight Joint

From the south-east corner of the present-day Temple Mount, the eastern wall shows Herodian masonry for some 106 feet. At that point a seam, or straight joint, is visible, to the north of which Hasmonean masonry appears followed by the oldest masonry believed to perhaps be that of Hezekiah. All of the upper courses of the wall are muslim. 

The Millo or Akra is the high place. Those on high ground have the advantage in war.

The Arka was built in Grecian fashion having two rounded walls in the shape of a crescent moon.

Another word for Millo is Acra in the Grecian language.

Josephus explains what happened to the Acra/millo in Jerusalem.

 Josephus.  Wars Book V cp lV
1. THE city of Jerusalem was fortified with three walls, on such parts as were not encompassed with unpassable valleys; for in such places it had but one wall. 

(These walls are depicted on the bright colored map above)

...The city was built upon two hills, which are opposite to one another, and have a valley to divide them asunder; at which valley the corresponding rows of houses on both hills end. 

(The two hills would be the western hill and the eastern hill)

...Of these (two) hills, that which contains the upper city is much higher, and in length more direct. Accordingly, it was called the "Citadel," by king David; he was the father of that Solomon who built this temple at the first; but it is by us called the "Upper Market-place."

(Notice that the western Hill is what David called the Citadel. In the time of Josephus they called it the Upper Market Place. This does not mean that the only thing on that western hill was just a market place. But still the whole hill was referred to the "upper market place" in his day)

...But the other hill, which was called "Acra," and sustains the lower city, is of the shape of a moon when she is horned; over against this there was a third hill (Bezetha on the map), but naturally lower than Acra, and parted formerly from the other by a broad valley. However, in those times when the Asamoneans reigned, they filled up that valley with earth, and had a mind to join the city to the temple.

(What is important to understand, is that the Eastern hill was the whole hill, defined by its highest point, (where the Dome of the Rock now sits), to the lowest part of the hill at the southern end of the city of David.  It is the Eastern hill.  This hill as a whole was called the Acre/Akra. It doesn't mean that the whole hill was the Acra, just as the whole western hill was not just one big "Upper Market Place". It is the Hill where the upper market place was located, just as the eastern hill is where the Acra was located, defining it. 

The hill itself from the northern end of the hill to the lower part of the hill to the south, called lower city, was not shaped like a moon when it is horned, like some believe, only the Acra was of that shape. The Acra was a fortified wall with it's accompanying Towers, making it a fortress. 

Across from this Acra, which was shaped like a moon when horned, was a third hill that was lower than the hill the Acra was on. But was directly across from the Acra fortress.  This would be the New City, Bezetha, which was encompassed with the third city wall.  (See its location on the colored map above.)  Josephus says this third hill was directly across from the Acra, which places the Acra on the northern end of the Eastern Hill directly across from Bezetha. 
Bezetha was north and west of the eastern hill, separated from the eastern hill by the Cheesemongers valley)

Josephus continues: They then took off part of the height of Acra, and reduced it to be of less elevation than it was before, that the temple might be superior to it. 

(These double, dirt filled, walls called the Acra were built by the Seleucids, replacing the old Millo which they had most likely broken through when capturing the city of Jerusalem. 
 

A Millo already  existed when David captured Jerusalem. David then built upon the Millo. 
The Hasmonean Jews razed the Acra and then built the Baris, also located across from the third hill as the fort/tower to protect the Temple and city from armies attacking from the north. 
Herod later broke through the Baris when capturing the city. Herod then built Fort Antonia in its place, which was broken through by Titus when he took the city.  The North side of the eastern hill was the only place that did not have a deep valley for protection, but was actually a land bridge between the eastern hill and the hill to it's north,  For this reason they also dug a Moat to separate the third hill (Bezetha) from the eastern hill.

There is more than just one millo mentioned in the scriptures.

Jdg 9:6 And all the men of Shechem  gathered together, and all the house of Millo, and went, and made Abimelech king, by the plain of the pillar that [was] in Shechem. 

2Sa 5:9 So David dwelt in the fort, and called it the city of David. And David built round about  from Millo and inward
. 
1Ki 9:15 And this [is] the reason of the levy which king Solomon raised; for to build the house of the LORD, and his own house, and Millo, and the wall of Jerusalem, and Hazor, and Megiddo, and Gezer 

2Ki 12:20 And his servants arose, and made a conspiracy, and slew Joash in the house of Millo, which goeth down to Silla.

Millos were built at a cities weakest point:

.We can read that there was a millo in the town of Shechem. 

A millo which goeth down to Silla (town outside Jerusalem)

There was a millo in the city of David.

After Solomon built his house he also built a millo.
 
 
 
 

The Secret passage

THE ANTIQUITIES OF THE JEWS
Book 15, Chapter 11
 

7. There was also an occult (underground)passage built for the king; it led from Antonia to the inner temple, at its eastern gate; over which he also erected for himself a tower, that he might have the opportunity of a subterraneous ascent to the temple, in order to guard against any sedition which might be made by the people against their kings.

Warren's Description of a passage
Cistern No. V, under platform to the south-east of the "Dome of the Rock," descended; 48 feet deep, 2 feet water. This cistern has a curious cruciform shape; at the eastern end a low doorway cut in the rock leads to a flight of steps, which after ascending some distance in a southerly direction, turns sharp off to the east, and communicates with a subterranean passage; the passage is covered by a semicircular vault, and at its entrance to the cistern are the remains of a doorway; on the floor there was a thick slimy deposit, and a few yards beyond the doorway the opening was blocked up by earth; there are two openings to the cistern in use and one closed, below one of the former a rough basin has been made to collect the water from the different branches. No conduit could be seen entering the cistern; the roof of the south-eastern branch is of rock, but there was not sufficient light to see what that of the other portion was made of.