This tower together with its twin across Lough Foyle at Greencastle in Co Donegal was built in 1812 to guard the mouth of the Foyle against Napoleonic invasion.

There are beautiful views from here of the Inishowen peninsula.

The city walls were built between the years of 1613 - 18, to guard the new settlement of the London merchants. The four original gates have been remodeled, including the Bishops gate which was closed against the advancing army of King James II, by a group of apprentices boys in 1688. It as thanks to these walls that the city was able to withstand the 105 day siege which ensued.

Still in place on the battlemented walls are some of the cannons used in the siege, it is possible to walk along about three quarters of the length of the walls. The best point of access to the walls today is by way of steps leading from Shipquay behind St. Columb's cathedral.