The Forum is usually approached from the west side by the short, steep street leading from the Porta Marina. Entering, we find ourselves near the lower end of an oblong open space (Plate I), at the upper end of which, toward Vesuvius, stands a high platform of masonry with the ruins of a temple--the temple of Jupiter; the remains of a colonnade are seen on each of the other three sides. Including the colonnade the Forum measures approximately 497 feet in length by 156 in breadth; without it the dimensions are 467 and 126 feet. The north side, at the left of the temple, is enclosed by a wall in which there are two openings, one at the end of the colonnade, the other between this and the temple; at the right the wall bounding the open space has been replaced by a stately commemorative arch, while the end of the colonnade is closed by a wall with a passageway. Another arch, of much simpler construction, stands at the left of the temple, in line with the façade; it cuts off the area between the temple and the colonnade from the rest of the Forum. A third arch once stood in a corresponding position at the right. The colonnade is nowhere intersected by a street passable for vehicles. Even the entrances on the north side form no exception. At the left you descend to the area by several steps, at the right by one only; yet here the exclusion of carts and wagons was made doubly sure by placing three upright stones in the passageway. Only pedestrians could enter the Forum, and they, too, could easily be shut out by means of gates in the entrances; the places where the gates swung can still be seen in the pavement, and one of them is shown in a painting (Fig. 16). No private houses opened on this area; it was wholly given up to the public life of the city and was surrounded by temples, markets, and buildings devoted to the civic administration. The colonnade was not uniform in character upon all the three sides. As will be seen from our plan (Plan II), on the south side, and on the adjoining portion of the east side as far as Abbondanza Street, it was constructed with two rows of columns and had a double depth. On the east side, north of this street, the porticos in front of four successive buildings (K, L, M, N) took its place. For the greater part of its extent the colonnade was built in two stories, the lower of the Doric, the upper of the Ionic order. The upper gallery was made accessible by three stairways, at the southeast and southwest corners of the Forum and at the middle of the west side; on the east side it did not extend beyond Abbondanza Street.