The Derry Walls, also known as the Walls of Derry, were built in the early 17th century to protect Scottish and English settlers in Ulster. They survived the Siege of Derry in 1689 and have become a symbol of the city's resilience. The walls are about a mile long, with seven gates and 22 cannons lining them. Despite some turbulent times during The Troubles, the walls remain a key landmark in Derry, offering a historic stroll around the city center.