FOURTH ROOM.--Landscapes, by Poussin; Battle-pieces, by Wouvermans; Sea-shore, by Rosa; Cabinet, with reliefs in ivory; Subjects from the Sistine Chapel. THE GREAT HALL.--Ornamented with statues and mirrors. Assumption, by Rubens; Roman Charity, by Subtermans; Ecce Homo, by Albano; Narcissus, by Tintoretto; Venus, by Vasari; Rape of the Sabines, by Ghirlandajo; S. Peter, Madonna, and Child, by Palma Vecchio; Venus and Cupid, by Bronzino; another, by Salviati; Madonna Liberating a Child from the Demon, by Nicolo da Poligno. SIXTH ROOM.--The _Colonna Bellica_, surmounted by a statue of Mars, with low reliefs round the column. In the Via dei Fornari, _on the right_, at No. 21, lived Michael Angelo. _Crossing the new Via Nazionale, either of the streets on the sides of the Prefettura leads into_ THE FORUM OF TRAJAN. This was the largest and grandest of all the fora, being built to one design by the celebrated architect Apollodorus of Damascus (Dion Cassius). No author has given us any detailed account of the beautiful group of buildings that formed this forum, but what passages there are tend to show its magnificence. There was first of all an open space, or the forum proper, surrounded by a double row of shops, one above the other. In the centre of this space was the colossal equestrian statue of the emperor (Marcellinus, xvi. 10). Beyond this, crossing the whole width of the forum, was the basilica called, after the family name of the emperor, Ulpia. Beyond this was the celebrated pillar, behind which stood the Temple of Trajan, with the libraries on either side. The portion excavated is only a small piece of the whole, which extends under the houses all round. The size of the basilica can be made out from the gray granite pillars which once supported the roof. It was sometimes called the Hall of Liberty, from the slaves receiving their freedom here. THE COLUMN OF TRAJAN. A magnificent marble pillar, the pedestal of which concealed the chamber where the ashes of the emperor were deposited. The bas-reliefs on the basement are among the most beautiful decorations of ancient or modern times; they represent the arms taken from the Dacians, against whom Trajan had made several campaigns. It marks the height of the Quirinal Hill, cut away to make the open space for the Forum of Trajan in which it stands. A series of bas-reliefs, representing the Dacian war, forms a spiral round the shaft of the pillar. Erected A.D. 114. It is 127 feet high, including the base, and is surmounted by a statue of S. Peter, 11 feet high, placed there by Sixtus V. in the sixteenth century. The pillar is composed of thirty-four blocks of white marble. The reliefs are two feet high at the bottom, and gradually increase in size as they go upwards, thus making the figures at the top and bottom seem of equal size. There are two thousand five hundred figures, besides animals and other details.