Some of the earliest known examples of colored window glass, datable to c. 800–820, were recovered in excavations at the Abbey of San Vicenzo in Volturno, Italy.[3] Glass of the same colour ranges and similar date is also found in England, at the monastic sites of Jarrow and Monkwearmouth, and at other sites in the north of England.[4][5] These examples are not painted. However, it was not until the advent of the monumental cathedral and church building campaigns in the 11th and 12th centuries that the demand for colored glass began to increase significantly, reaching its highest level in the 14th and 15th centuries. The oldest surviving stained glass windows still in situ are thought to be the Prophet Windows in Augsburg Cathedral, of c. 1065.