St. Johann is the older of Schaffhausen's two main churches, with foundations going back to the 9th century and a pre-Romanesque crypt that is one of the earliest surviving examples of church architecture in the canton. Most visitors head straight for the Münster — the larger, more prominent Romanesque minster nearby — but St. Johann rewards the detour. The crypt in particular is simple and cool and surprisingly moving for its age.
The church sits in a quiet courtyard adjacent to the Museum zu Allerheiligen, and the two are worth visiting together. Services are still held here, which means access is occasionally restricted, but outside service times the building is generally open. The absence of tourist crowds makes it one of the more genuinely tranquil spots in the old town.