Located in the center of the old town, the 'Spalenhof' is one of Basel's most important buildings. Dating from the 13th century, it was converted into a merchant's home in the 15th and 16th centuries and was sold to the city in 1956. New apartments were planned as part of a program to upgrade the district as a residential area. In 1984, a preliminary investigation into the building's condition revealed that the Kaisersaal's roof structure at 12 x 12 meters was too huge by medieval standards, along with its massive, timber post-and-beam system and a painted cassette ceiling.
Two cabaret theaters had been created in the Kaisersaal in the 1970s: the Fauteuil in the basement, and the Tabourettli on the first floor. In the center of the building, the main timber beam had sunk, a problem that was compounded by the removal of three supports to create an unobstructed space in the Tabourettli's auditorium. Calatrava proposed suspending the ceiling, a load of 211 tons. The Kaisersaal's main beam was thereby relieved by the addition of a braced, triangulated structure embedded within the partition walls, distributing some of the load to the outside masonry. Support tension rods of brushed steel were suspended down through the building to carry the theater ceiling below, which now has an acoustic function.
The new bracing forms a functional and modern counterpoint to the ancient framework. The acoustic ceiling of the theater is comprised of elongated, tapering panels of pear wood. The window shutters, which resemble winged lapels, fold upward. When closed, the shaped entrance door is designed to reveal a side entrance for late-comers. The bar, light fittings and furniture were also designed by Calatrava. His cloak room in the anteroom features an octagonal box that can be folded open for use — an exploration of a transformational, geometric object.
1986 - 1987