Y Gaer was an important Roman fort with a garrison of 500 cavalry recruited from Spain. It was built about AD75 during the conquest of Wales, and lies near a Roman crossroads. Sir Mortimer Wheeler excavated part of the site in the 1920s. Sections of wall and the remains of gates and guard towers are still clearly visible. The fort lies on a hill at Y Gaer farm two miles west of Brecon, overlooking the confluence of the rivers Usk and Ysgir.
