III. A large rectangular brick edifice with three windows on each side. In the interior are the remains of ornamental niches, Corinthian capitals, and a marble cornice. The walls have rivets upon them, by which it appears that they were covered with a marble casing, and the magnificent block of African marble which serves as the threshold shows that the building was of a costly description. Traces have been found of a front chamber with a portico of grey granite columns. Whether this was a temple or not is uncertain, but it has been supposed that the arrangements in the interior would agree with such a supposition. The masonry may be assigned to the age of Trajan or Hadrian. The name of Vulcan has been usually given to this temple, which was at one end of the ancient forum. Many excavations have been made here within the last ten years, and some valuable works of art have been discovered, and numerous stores and shops of various kinds have been uncovered. IV. The ruins of a theatre supposed by Nibby to be that mentioned in the Acta Martyrum, near which S. Quiriacus and S. Maximus, and S. Archelaus, and a number of others were martyred. It is built partly of yellow and red brickwork, and partly of opus reticulatum, and apparently belongs to the restorations and additions made by Hadrian to the city. V. The ruins of an extensive building, probably an emporium, on the bank of the river near Torre Bovacciano. In this place a great number of works of art were discovered by Fagan in 1797, showing the magnificent decorations with which the building was ornamented; and several inscriptions with the names of Severus and Caracalla found here are given by Nibby.[152] [Sidenote: Grove of the Arval College.]