nature of an observatory, though whether in connection with Sun or Star worship it is of course impossible to say. [Illustration: THE CARACOL ("WINDING STAIRCASE"), CHICHEN ITZA.] [Illustration: THE TENNIS COURT, CHICHEN ITZA.] To the south of the Caracol stands a ruin of remarkable beauty and in wonderful preservation. The Spaniards called it "_La Casa de las Monjas_" (Nuns' House), and there is much reason to believe that this is a thoroughly appropriate title, and that this building did actually house those virgins of noble birth of whose dedication to religious uses we shall have to speak at some length in a later chapter, when reviewing the whole subject of Mayan religion. The peculiar feature of the building is the manner of erection. Apparently at first it stood on a solid foundation of masonry 30 feet high and of the same size as the building itself except to the north, where there was a platform 30 feet wide. At some period, whether during erection or after completion it is impossible to tell, the architect must have come to the conclusion that the building was top-heavy, and decided to strengthen it by continuing the northern platform all round. This new wall was not spliced and mortised into the other as one would expect. A wall was built to the outer dimensions of the support only 2 feet thick, and the space between this and the main building was filled up with rubble and loose building waste. The abutment on the northern side, down which thirty-four steps lead to ground-level, was built in the same manner, giving it an unsubstantial lean-to appearance. But we shall have more to say upon this mode of building when attempting to date these structures in a later chapter. The buildings on the platform are two in number. The larger is 104 feet long and 30 wide, and contains seven rooms, the largest on the south side measuring 47 feet by 9 feet wide, its inner walls bearing traces of figure paintings from floor to roof. The space on the northern side corresponding to this room has apparently been filled up. The niches for the doorways exist, but they are sealed to the lintel with masonry, whether because sepulchral or to give support to the building above, it is impossible to say. On either side of this closed space are two smaller rooms and two more in corresponding places on the south side, while at the east and west ends a room runs from north to south. The lintels of the three sealed doorways, both underneath and on the facings, are covered with hieroglyphics, as are also those of the doors on either side, and the fact that none are found on the southern chamber suggests that the sealing was for an important reason. Returning to the north side and climbing sixteen steps, you reach the second platform, on which stood a second house now merely a heap of stones. It was one-roomed with two doors, looking north and south.