This enormous mass of building consisted of a central oblong block, containing all the halls and chambers appropriated more immediately to the baths, and a surrounding court, the sides of which were formed by gymnasia and other places of amusement, and the area of which was laid out in gardens, with shrubberies, ornamental colonnades, and fountains. A similar arrangement is found in the Thermæ of Titus and Diocletian. The central block of buildings contained four immense halls and a rotunda, around which numerous smaller rooms were grouped. The first of these large halls (a) was entered from the north-eastern side by two wide doorways. Rows of niches for sculpture broke the broad inner surfaces of its walls, and it communicated with the chambers on each side by open passages filled with columns of splendid marble and granite. The floor formed an immense basin shaped hollow, showing that the purpose for which it was used was that of a cold swimming-bath. The steps by which the bathers descended into it have been found at the two shorter sides, and on both sides are chambers for dressing and undressing. In the centre of the group of buildings is another hall (b) of nearly the same dimensions as the cold bath, with large recesses at both ends. The floor of this was paved with the richest marbles. The four lateral circular recesses formed hot baths, and were fitted with steps and seats of various kinds for bathers. In the recesses at the ends stood two enormous porphyry basins, one of which is now preserved in the Museum at Naples. This hall was probably the tepidarium and had a very lofty roof supported by eight granite pillars of colossal size, and by a network of brazen or copper rods. One of the pillars was given to Duke Cosmo I. by Pius IV., and stands in the Piazza di Trinità in Florence. The smaller chambers (c) (d) (e), at the western and southern angles of the tepidarium, contained the apparatus for heating water. These chambers, the purpose of which is unknown, separate the tepidarium from the rotunda (f). The position of this latter and its shape would seem to indicate that it was a laconicum or hot-air room, but the state of the ruins is at present such as to preclude any positive assertion as to its purpose.