The castle in Wales famous for its "Leaning Tower" is Caerphilly Castle (Castell Caerffili), located in South Wales. This massive medieval fortress is the second-largest castle in Britain, trailing only Windsor. Its iconic southeast tower leans at a precarious angle of approximately 10 degrees, which is actually a steeper tilt than that of the Leaning Tower of Pisa. The lean is widely believed to be the result of damage sustained during the English Civil War in the 17th century, likely from an attempt by parliamentary forces to "slight" or destroy the castle using gunpowder. Despite the structural damage, the tower remains stable and has become the castle's most photographed feature. In 2026, visitors can explore the recently refurbished Great Hall and inner wards, though the leaning tower remains a strictly external marvel, standing as a testament to the castle’s resilience against centuries of siege and decay.