The Skansin Fort:
According to legend, this stone fort was constructed in 1580 by Faroese national hero Magnus Heinason to protect Tórshavn from pirates. It didn't work all that well against foreign powers, however: the fort was destroyed by the French in 1677 and again by the British in 1808. The fort was constructed in its present form by the Danish in the early 19th Century. The fort was also used as a command post by the British during World War II. Today, you can wander through the stone works, admire the modern lighthouse in its midst, and enjoy views of the area.
There's not all that much to the fort, but it's worth a look. There are some cannons are on the fort, and it offers some good views both of Tórshavn and across the bay to the island of Nolsoy.
On top of the fort is a lighthouse.
Address: Right next to the ferry terminal, Near the lighthouse,Torshavn