If you're looking for something free to do that keeps you out in the fresh air whilst still feeling like a tourist, then you've got to walk the perimeter of the 17th-century city walls that surround Derry.
This is one of the most beautiful examples of a Walled European City! The walls went up between 1613 and 1618 as a defence for early 17th-century settlers from England and Scotland.
The walls span a whopping 1.5km and they form a walkway around the inner-city - perfect for sight-seeing!
It's totally free to explore the walls yourself, but if you're a fan of a walking tour then pop to the visitor information centre to join a tour and learn about the wall's colourful history.
Concessions: Free entry