Surrounded by two arms of the River Ill, the Grande Ile (Big Island) is the historic centre of the Alsatian capital. It has an outstanding complex of monuments within a fairly small area. The cathedral, the four ancient churches and the Palais Rohan – former residence of the prince-bishops – far from appearing as isolated monuments, form a district that is characteristic of a medieval town and illustrates Strasbourg's evolution from the 15th to the 18th century.

Źródło: World Heritage Convention
http://whc.unesco.org/en/list/495