On the north-west side it is bounded by a well-built wall 4 ft. 6 in. high and 12 ft. long, at the north-east end of which is a large rounded buttress with portcullis groove. This buttress projects 3 ft. into the passage, and is 3 ft. 6 in. high. Probably another buttress containing a corresponding portcullis groove faced it on the opposite side of the passage.
The eastern side is bounded by the entrance to the Outer Parallel Passage and by the north wall of that passage, which curves round in front of the North Entrance to the temple, and runs at right angles to its former position. This wall, which is well built, is 7 ft. high, and forms the east side of the passage for some 35 ft., but at this point it is reduced to 3 ft. in height, and is carried on toward the north-east in a less carefully constructed style.
The widths of the passage and the heights of the side walls, measuring from the North Entrance to the temple, are as follows:—
| Heights. | |||
| Width. | West side. | East side. | |
| S. Extremity | 12 ft. | 4 ft. 6 in. | 7 ft. |
| 25 ft. | 5 ft. | 2 ft. 6 in. | 6 ft. |
| 35 ft. | 2 ft. 10 in. | 3 ft. | 4 ft. |
| 50 ft. | 2 ft. 6 in. | 3 ft. | 3 ft. |
Between 35 ft. and 50 ft. are remains of pavement.
This passage, with its length of 660 ft., is believed to have formed the chief line of communication between the Elliptical Temple and the Acropolis, seeing that it runs from the main entrance of the temple down into the valley at a point almost facing the lowest extremity of the South-East Ancient Ascent to the Acropolis.
OUTER PARALLEL PASSAGE
On leaving the temple by the North Entrance one enters a walled-in area. This area is formed by the southern extremity of the North-East Passage and the western extremity of the Outer Parallel Passage, both of which meet at, and converge upon, the North Entrance.
The Outer Parallel Passage runs for 125 ft. east-south-east from the North Entrance parallel with the north-east wall of the temple between the points [450 ft.] and [575 ft.] of its outer circumference. At its extremity near the North Entrance this passage is 7 ft. wide, and 25 ft. further east-south-east of the entrance it is 3 ft. 8 in. wide, which width is maintained for a length of 50 ft., beyond which point it commences to widen out till the east-south-east extremity is reached, where it is 12 ft. 6 in. wide.
Opposite the North Entrance the outer wall of the passage is 6 ft. high; at 25 ft. further east-south-east, 5 ft.; at 75 ft., 8 ft.; at 100 ft., 7 ft.; and at 125 ft., 5 ft., the line of summit from the 25 ft. point to the east-south-east extremity being fairly level throughout. This outer wall is well built. It is 4 ft. 2 in. wide on the summit at 5 ft. from the floor of the passage, and 3 ft. 10 in. wide at 7 ft. from the ground.