Reichenau Island () is an island in Lake Constance in Southern Germany. It lies almost due west of the city of Konstanz, between the Gnadensee and the Untersee, two parts of Lake Constance. With a total land surface of and a circumference of , the island is long and wide at its greatest extent. The highest point, the Hochwart, stands some above the lake surface and above mean sea level.
Reichenau is connected to the mainland by a causeway, completed in 1838, which is intersected between the ruins of Schopflen Castle and the eastern end of Reichenau Island by a and waterway, the Bruckgraben. A low road bridge allows the passage of ordinary boats but not of sailing-boats.
Reichenau Abbey, founded on the island by bishop Pirmin in 724, quickly developed into an influential religious, cultural, and intellectual center. Because of its historical importance and the exceptional quality of the architecture and artwork found in the island's three churches and abbey, Reichenau was declared a World Heritage Site in 2000.
History
Although people occupied Reichenau in the Bronze Age and Iron Age, archeological evidence suggests that Reichenau was abandoned during the Roman era. It remained uninhabited until 724, when the monk Pirmin received support from the Carolingian ruler Charles Martel to build a monastery on the island. In the early 9th century, under the patronage of the Carolingian dynasty and Ottonian dynasty, the community flourished. In 816 the monastery church of the by-then abbey, was rebuilt in a cruciform basilica style, and churches dedicated to the Virgin and Saint Mark were consecrated.