He was now entering, after forty-two years, upon the last stage of his long life.

Before the end came, he gave final form to the main features of the great basilica, raising the dome which dominates the Roman landscape like a stationary cloud upon the sky-line.

What had happened to the edifice in the interval between 1505 and 1547 must be briefly narrated, although it is not within the scope of this work to give a complete history of the building.
Bramante's original design had been to construct the church in the form of a Greek cross, with four large semi-circular apses.

The four angles made by the projecting arms of the cross were to be filled in with a complex but well-ordered scheme of shrines and chapels, so that externally the edifice would have presented the aspect of a square.
The central piers, at the point of junction between the arms of the cross, supported a broad shallow dome, modelled upon that of the Pantheon.

Similar domes of lesser dimensions crowned the out-buildings.