In his first year as Court architect and engineer, Johann Balthasar Neumann was charged with designing and building a new Residenz, in Würzburg, from the ground up, for the Prince-Bishops of Schönbrunn. As Neumann was often called away to other projects, his plans were carried out mostly by architects favored by the Prince-Bishop’s uncle and brother, including Lucas von Hildebrandt, Maximilian von Welsch and Germain Boffrand. The stone and masonry exterior was completed in 1744; the interior of the 300-room palace was finished in 1770. After Neumann’s death in 1753, Hildebrandt, Welsch and Boffrand each took full credit for the Residenz’s design in its entirety.
Neumann oversaw the building and decoration of the most important spaces in the Residenz, the suite of formal and ceremonial rooms and antechambers through which visitors passed on their way from the carriage entrance on the ground level to the Kaisersaal on the upper, where the Prince-Bishop would receive them. The centerpiece of this progression is the Treppenhaus, built in 1737. The grand, indoor staircase is the cold-climate equivalent of the double-ramp stairways seen on the exteriors of Italian villas.
Neumann had to get guests up one floor in a manner befitting their rank, without taxing them physically, and while preparing them, step-by-step, as it were, for the magnificence of the Prince-Bishop. Neumann devised a scheme whereby the two stages of the stair, which reverses direction at midpoint, forms a cantilever, allowing the huge mass of stone to be carried on think columns, giving the impression it floats on the air. In Rococo Bavaria, one did not climb or mount the stair, one ascended, drifting upwards towards the vast pastel empyrean above.
The entire span of the Treppenhaus (18m x 30m) is covered by a vast vault composed of rubble and concrete that has no supports other the the walls it rides on. Neumann’s critics warned of collapse; the vault is not only still intact today
, it survived direct hits during the Allied bombing of Würzburg on 16 May 1945, which largely destroyed the old city and much of the Residenz. Neumann made use the vault’s weight, the downward thrust of which clamps the cantilever in place at both ends. By engaging the staircase to the wall the staircase acts as a strainer arch would, countering the tendency of the walls to buckle under the load of the vault. It is a mutually-reinforcing structural solution of great elegance.
A second Treppenhaus of equal dimensions was planned for the other side of the Kaisersaal, but was never begun.
The Treppenhaus vault was frescoed by Giovanni Battista Tiepolo in 1752-53. Measuring 670m², it is the largest painting in the world painted by the highest-paid artist of the 18th century ( Tiepolo was paid 15,000 gulden, for his work at the Residenz, over 13 times the annual salary Neumann drew from his court appointment). The fresco represents an allegory of the the world, represented by the four continents no less, paying tribute to the Brince-Bishop. The fresco includes a portrait of Neumann, dressed in his Officer’s uniform, seated on a canon. A trompe l’oeil dog sniffs at his outstretched hand. Canon and dog must have been inside jokes between the painter and architect. Balthasar Neumann died in Würzburg just as Tiepolo was finishing the fresco, in the late summer of 1753.