aerial photograph of Tonbridge Castle Tonbridge Kent England UK. Tonbridge Castle was first constructed as a Norman Motte & Bailey Castle in the 11th century, shortly after the Norman Conquest. The original wooden structure was soon rebuilt in stone and the magnificent medieval gatehouse which dominates the site today was constructed in the 13th century. The Castle was refortified during the English civil war but thereafter fell into disuse and the stone used in the construction of nearby bridges and locks. The Georgian Manor House was constructed on the site at the end of the 18th Century.