The whole space between the Quirinal and the Capitoline Hills was occupied by the immense Forum and public buildings which Trajan constructed. The Column of Trajan, with its wonderful spiral reliefs, still marks the site of this great mass of masonry; but the remainder, which included a basilica, two libraries, a temple, and two extensive porticoes, has disappeared with the exception of a fragmentary ruin in the Via della Salita del Grillo under the Quirinal. This ruin is the remains of a part of the great semicircular side of Trajan’s Forum under the Quirinal Hill. It consists of a brick building of two stories high, containing in the lower story small rooms measuring about ten feet square, probably shops or offices for notaries and lawyers’ clerks. The interior of three of the rooms is covered with plaster, and painted roughly. The floors were covered with mosaic pavement of a common kind, of which much still remains in situ. Above these rooms runs a corridor with arched windows, at the back of which a row of large and high chambers opens, resting upon the natural rock of the Quirinal Hill. The front is faced with brick pilasters on travertine basements, in a mixed Doric and Ionic style, and there were formerly pediments over the windows. It will be seen by reference to the plan that a small portion of the Forum of Trajan can be now seen in the Piazza della Colonna Trajana. The arch from which the beautiful bas-reliefs on Constantine’s Arch were robbed, probably stood in the Via del Priorato at some distance from the Piazza. The two double rows of bases now to be seen in the Piazza formed a part of the great Basilica Ulpia, part of the ground-plan of which is still preserved on two fragments of the Capitoline map. Many fragments are to be seen here of the columns which supported the roof of the basilica, among which those of grey granite, probably belonging to the outer rows of columns, are most conspicuous. [Sidenote: Column of Trajan.]