The Osteiner Hof is one of several Baroque-era palatial mansions along Schillerplatz square in the German city of Mainz. The mansion, along the southern edge of the square, was built in 1747-1752 by architect-soldier Johann Valentin Thomann for Franz Wolfgang Damian von Ostein, brother of Johann Friedrich Karl von Ostein, who was prince-bishop of Mainz at that time.
Characteristic features for this building are the three round protrusions at the front entrance and on the two corners. The building is lavishly decorated; for instance, the windows are framed by rococo-style cartouches symbolising the elements of air, earth and water. The classical gods Diana and Mars are shown on the cartouches framing the balcony doors.
Wikipedia https://en.wikipedia.org/wiki/Osteiner_Hof
Coordinates 49°59'51.44" N 8°16'5.867" E