9. The excavations at Utrecht were quite limited in scope so the number of Early Medieval finds is rather small. However, the reuse of the castellum as the seat of the Frisian missionary episcopate is historically documented. Early Medieval reuse of the castellum at Valkenburg (Zuid-Holland) is evidenced by just one grave from the early eighth century (Stein 1967, 401, Liste 2, Tafel 99). The excavations failed to shed much light on the history of this castellum after the Middle Roman period. Theoretically, the single rich grave may belong to a cemetery around a (private) chapel in a manorial centre.