Falmouth is a resort and port in south-western England. It is located on the southern Cornish coast at the entrance to the large and sheltered natural harbour of Carrick Roads, a drowned valley at the junction of seven rivers. The harbour is popular with pleasure craft and Falmouth has several boat-building yards and a major ship repair yard. The Pendennis and St Mawes castles face each other across the Roads. They were built by Henry VIII in the 16th century to guard the entrance to the Roads; the protection they offered played an important part in Falmouth's development as a port.