The brick walls of Castelfranco are the reason most visitors stop here. Built around the year 1200 as a Trevisan border fort against Padua, they form a near-square enclosure roughly 230 metres on a side, with corner towers and a tall belfry rising from the western side. The moat survives on three sides and has been planted with lime trees and grass, making a quiet circular park around the walls.
The best way to take it in is to walk the full perimeter on the outer path, then enter through one of the four medieval gates. The brickwork is largely original, patched and refaced over the centuries but coherent. The walls are floodlit at night and look extraordinary from the moat path, especially in winter mist when the towers loom from the dark. A small fee gets you up onto the watchtower for views over the town and the surrounding plain — on clear days the Dolomites form the northern horizon.