Mahon

Mahon is the capital of Menorca and became so during the British rule  (1708-1756 later 1798-1802). Founded originally by the Carthaginians, legend being General Magon, brother of Hannibal, named the town. The architecture of Mahon is varied & cosmopolitan, with an English influence in many parts, combining open spaces with many narrow streets and passages. Much of the islands administration & public services are concentrated in the town. In medieval times the town was walled. The San Roque Arch (app 1500 a.d) being virtually the only remaining part of the old walls.  
The focal point for Mahon is the magnificent harbour (the second largest natural harbour in the world after Pearl harbour). At the port entrance, the most easterly point of Spanish territory is the fort of La Mola, used by the military and until 1968 Spain's most notorious jail.
A good way to see the harbour is from one of the many boat trips, some trips even venture out for the whole day to remote beaches.
It is rumoured Lord Nelson stayed on Golden Farm with Lady Hamilton overlooking the harbour, he certainly visited the island but there is no evidence he stayed on the farm.
There are bars and restaurants all along the quay side, and there's nothing better on a summer's evening than watching the yachts and large cruisers coming and going.