In the Via di S. Maria in Cacaberis, No. 23, there are two Doric columns of travertine half buried in the around, with a portion of entablature above them, and between them an ancient brick arch forming the entrance to a stable. In the interior of the stable are two other similar arches and columns, and above these there are indications of an upper story. Other ruins of the same description are built into the next house, No. 22, and into several other houses near. In the sixteenth century, the Bolognese architect Serlio saw more ruins here, and he represents in his sketch an upper story with Corinthian pillars. The name Crypta Balbi, which is found in the catalogue of places in the ninth region, has been given with much probability to these ruins. A crypta, or cryptoporticus, according to Pliny, was a covered corridor with windows, which could be shut or opened at pleasure. Such a building was used for exercise in wet or hot weather. Some were open on one side, others closed on both sides. A cryptoporticus of the latter kind is to be seen in the ruins of Nero’s Domus Aurea under the baths of Titus. The ruins in the Via di Cacaberis appear to have had open arches at the sides. This cryptoporticus was probably attached to the Theatre of Balbus, as the portions Pompeii was to the Theatrum Pompeii, and Venuti thinks that it extended along the back of the scena, and that it was intended as a place of shelter for the spectators in case of the sudden showers of rain peculiar to the Roman climate.[87] The name of the street Cacaberis or Caccavari has been derived from crypticula. The Mirabilia, an ancient list of the sights in Rome, calls these ruins Templum Craticulæ. [Illustration: The Circus Flaminius from Nolli’s Map, Pl. 19.] [Sidenote: Circus Flaminius.] The Circus Flaminius, named from the Flaminian family of ancient Rome, lay in the quarter traversed by the Via delle Botteghe Oscure, and in the neighbourhood of the Palazzo Mattei. The Circus was destroyed before the 9th century, and there are now no traces of it left to guide us, but before the erection, in the 15th century, of the larger houses in this quarter, some few ruins appear to have been visible in the neighbourhood of the Palazzo Mattei. These are described by Andrea Fulvio and Ligorio as having belonged to the Circus Flaminius, and according to their account the length of the Circus lay in a direction from west to east, and reached from the Palazzo Mattei, where the semicircular end was situated, to the Piazzo Margana where the starting-point lay. A tower, now called the Torre Citrangole, was once called the Torre Metangole, and marked the spot where the goal of the Circus stood. [Sidenote: Theatre of Pompeius.]