Faced with the thousand pieces of the Marble Plan, archaeologists play the fascinating game of making joins, as in a jigsaw puzzle. In 1899 Lanciani announced the discovery of a new fragment which joined with the piece of the Marble Plan already mentioned. It filled out the rectangular shape of the altar, added two more rows of garden-plots, and supplied another side to the portico, at right angles to the other. This side had two rows of columns, four of which were represented as of larger dimensions than the others, and as standing on plinths or square bases. These two fragments made possible restoration, on paper, of a considerable part of the Forum’s plan. Given the Roman architectural principle of axial symmetry, Lanciani could be sure that the altar belonged in the middle of one side of the portico-surrounded space, towards the back. He could restore two more column-bases; and, knowing that there must have been three rows of garden-plots on either side of the altar, and that the scale of the Marble Plan was 1:200, he could arrive at the original length of one inner side of the portico--about 325 feet. But there paper hypothesis had to rest, awaiting excavation. [Illustration: FIG. 9.2 Rome. _Forum Transitorium, Colonnacce_ before excavation.] [Illustration: FIG. 9.3 Rome. _Forum Transitorium, Colonnacce_ after excavation. (M. Scherer, _Marvels of Ancient Rome_, Pls. 162 and 165)] [Illustration: FIG. 9.4 Rome, Imperial Fora, model. (F. Castagnoli, _Roma antica_, Pl. 4)] The opportunity did not arise until 1934, in connection with systematizing and beautifying with lawns the borders of Mussolini’s grandiose new Via dell’ Impero, already mentioned as having been cut through slums from the Coliseum to the Piazza Venezia. The two projecting columns of the _Forum Transitorium_ (“Forum of Nerva”), southeast of the Forum of Augustus, were cleared, under the direction of A. M. Colini, of medieval and modern detritus down to their plinths (Figs. 9.2 and 9.3); the podium of the Temple of Minerva, at the end of this Forum, uncovered; and the _peperino_ wall behind the projecting columns isolated. Close in back of this wall, on the Forum of Peace side, Colini found large columns in African marble, which, he inferred, marked the missing northwest side of that Forum. Its general location had been known since 1818, but only now was there a _precise_ point in modern Rome’s subsoil from which, with the help of the Marble Plan, the true dimensions of Vespasian’s portico could be measured. Also, another fragment of the Marble Plan, not joining the two previously mentioned, showed the very stretch of wall and the columns which Colini had been excavating, as well as the plan of Minerva’s temple, whose podium he had uncovered.