At the entrance of the valley of the Circus Maximus, and on the south side of the Piazza della Bocca della Verità stands the church of S. Maria in Cosmedin which is built upon the ruins of an ancient temple. Ten columns still remain in their original places, seven of which stand in a line parallel to the entrance, and three others in the left-hand side wall of the church. Some of the columns are built into the walls of the Sacristies on the right of the entrance, and reach through the roofs to the upper story. The material of which they are made is white marble, and the order to which they belong the Composite. Parts of the wall of the cella may still be seen in the sacristy, built of tufa which was originally faced with marble. The design of the capitals and chiselling of the ornamental work upon them is of the best period of art, and one of them may conveniently be examined in the room over the sacraria, and in the organ loft. Behind the apse of the church are some large chambers built of massive blocks of travertine, which were probably attached to the Carceres of the Circus as stables or offices of some kind, and the position of these compels us to assume that the front of the temple faced towards the Velabrum, and that the seven columns parallel to the façade of the present church belonged to the side of the temple, while the three in the left-hand wall formed a part of the front. Otherwise the travertine chambers at the back must have formed some part of the temple, and it is difficult to see how this could have been the case, as they are evidently not the walls of the cella, and cannot be brought into any symmetrical position with the rows of columns.