Osteiner Hof

The building is lavishly decorated; for instance, the windows are framed by rococo-style cartouches symbolising the elements of air, earth and water.

After the left bank of the Rhine was occupied by French Revolutionary armies, the mansion was appropriated by the state, and in 1798 it became the seat of a newly created département of France, Mont-Tonnerre.

The building continued to be used as a seat of government after the Napoleonic era, even gaining the nickname Gouvernement during the years 1854-1859, while emperor-to-be Wilhelm I was serving as military governor of Mainz.

During the early days of the Franco-Prussian War (1870–1871), the Osteiner Hof served as military headquarters of a Prussian field marshal, Prince Frederick Charles of Prussia.

In 1914, then-military governor General Hugo von Kathen announced the start of World War I to the Mainz populace from the balcony of the Osteiner Hof.