"A vaulted passageway having its entrance in the west face of the terrace south of Structure VI, extends eastward some 17 m. Beyond this point, as though the passageway had not been completed, there is an irregular depression extending to the eastern edge of the terrace.
The passage is 1.70 m. wide; the vertical wall rises 1.92 m. the the vault, an additional 1.88 m. to the capstones, which have a span of 35 cm. It is approximately 30 cm. from the under side of the capstones to the roof."
(Ruppert & Denison 1943:59)