Bernhard Strigel, altar, altar of the Holy Cross
In 1507 the German painter Bernhard Strigel (Memmingen 1460–1527) created an altar of the Holy Cross of which four side panels have survived, while the presumably carved center has been lost. These four panels were formerly housed in Kynžvart (Königswart) Castle near Mariánské Lázne (Marienbad) in northwest Bohemia but were transferred to the National Gallery in Prague in 1972. The altar apparently was commissioned by the emperor Maximilian I and presented by him as a gift to Pope Julius II. Maximilian at this time was hoping to travel to Rome and to be crowned Holy Roman Emperor by the pope, as his father Frederick III had been in 1452. His plans came to naught, but the pope received the altar and placed it in Rome's Basilica of S. Paolo fuori le mura. More than three hundred years later Pope Gregory XVI (1831–1846) made a gift of the panels—the center of the altar was lost, perhaps in the great fire that devastated the basilica in 1823—to Count Clemens Lothar Wenzel von Metternich, the Austrian chancellor, who placed them in his castle at Kynžvart (Königswart). Hence they passed into the possession of the Czech Republic.
Pohlsander, Hans A.
"Four Altar Panels by Bernhard Strigel: Some Historical and Philological Perspectives,"
Quidditas: Vol. 19
, Article 4.
Available at: https://scholarsarchive.byu.edu/rmmra/vol19/iss1/4