"Figure 1 represents the ground plan of the three ranges, and gives the dimensions of the terraces. The north side of the second range has a curious and unaccountable feature. It is called the Casa Cerrada, or closed house, having ten doorways, all of which are blocked up inside with stone and mortar...In front of several were piles of stones, which [the Indians] had worked out from the doorways, and under the lintels were holes, through which we were able to crawl inside; and here we found ourselves in apartments filled up (except so far as they had been emptied by the Indians) with solid masses of mortar and stone. There were ten of these apartments in all, 220 feet long and ten feet deep, which being thus filled up, made the whole building a solid mass; and the strangest feature was that the filling up of the apartments must have been simultaneous with the erection of the buildings, for, as the filling-in rose above the tops of the doorways, the men who performed it never could have entered to their work through the doors. It must have been done as the walls were built, and the ceiling must have closed over a solid mass. Why this was so constructed it was impossible to say, unless the solid mass was required for the support of the upper terrace and building; and if this was the case, it would seem to have been much easier to erect a solid structure at once, without any division into apartments."
(Stephens, vol. 2, pp. 8-10)