Drake’s Island is one the most prominent landmarks in Plymouth and has played a key role in the history and development of the city. With a history dating back to pre historic times, the island is believed to be approximately 350 million years old. Scientists believe that island was formed around 400 million years. However, by 1090 the island was placed into the possession of Reginald de Valletort by William the Conqueror and comprised part of the Barony of Trematon. The first known structure on the island was the Chapel of St Michael, which had been built in 1135. Eventually, in 1270 this chapel was granted to the Priors of Plympton by the Valletort family and was eventually rededicated to St Nicholas. In 1440, the rights of the Priors of Plympton continued to be recognised, until the dissolution of the monasteries in 1536, when the Island reverted to the Crown.