In order to glimpse some of the earlier building façades buried by later construction, visitors are permitted to enter some of the tunnels beneath the East Court and Str. 10L-16 of the Acropolis.
"The early Acropolis (ca. 400-500) consisted of a huge platform that occupied the bulk of the southeastern quadrant of the later, fully developed Acropolis (its full eastward extent may never be known, owing to destruction by the Rio Copan). To the north a lower platform supported a large complex of multiroomed (unvaulted) masonry administrative/residential buildings, all underlying the later buildings of the northeastern quadrant of the Acropolis."
Robert Sharer, The Ancient Maya, p. 313