Please answer a question about the following article about Plymouth:

After the English Civil War the Royal Citadel was built in 1666 on the east end of Plymouth Hoe, to defend the port from naval attacks, suppress Plymothian Parliamentary leanings and to train the armed forces. Guided tours are available in the summer months. Further west is Smeaton's Tower, which was built in 1759 as a lighthouse on rocks 14 miles (23 km) off shore, but dismantled and the top two thirds rebuilt on the Hoe in 1877. It is open to the public and has views over the Plymouth Sound and the city from the lantern room. Plymouth has 20 war memorials of which nine are on The Hoe including: Plymouth Naval Memorial, to remember those killed in World Wars I and II, and the Armada Memorial, to commemorate the defeat of the Spanish Armada.

When was Smeaton's Tower first constructed?
1759