Reichenau

Reichenau Museum
Ergat 1 + 3
Adults €3, children €1.50
Apr – Oct: Tue-Sun 10:30-16:30; Jul & Aug: Tue-Sun 10:30-17:30; Nov–March Sat, Sun, public holidays 14:00-17:00
Schopflen castle ruins
free
at the end of the causeway, just before you're properly on the island

Originally served as a point of defense for the island at low tide. Destroyed in 1366. Now it's got a platform that allows you to watch part of the wildlife sanctuary.

St. Maria u. Markus Cathedral

This was the abbey church and reached its present shape in the 11th century. The treasury open Apr-Oct, 11:00-12:00 and 15:00-16:00, closed on Sundays contains relics of St. Mark, among other treasures. Behind the cathedral is an herb garden, a reconstruction of the abbey herb garden.

St. Peter and Paul Church

Features late Romanesque wall paintings from the early 1100's and has rococo ceilings from the 1750's.

Georgskirche
the first church you see upon arriving on the island

Contains relics of St. George, and wall paintings from circa 1000