The idea of building a larger church to replace St. Michael’s Chapel, which had been constructed west of the Rittersche Palast between 1588 and 1591, arose as early as the 1630’s. But a number of years were to pass before the cornerstone could be laid on 3 December 1666, St. Xavier’s Day, the feast-day of the patron saint of the prospective church. In 1669 the shell of the church was finished and the vaulting had been done. This was followed by the windows and the decoration of the main façade in 1672. The interior had not been quite completed when, with great Baroque pomp, the papal nuncio Edoardo Cibo consecrated the church on 29 August 1677. Several side altars and the high altar, which as a result of its high cost could be erected only in 1681, were still missing.