Smailholm Tower is one of many surviving peel towers. Barry designed a bridge with two bridge towers built on piers. He came up with the idea of building twin towers. The town was surrounded by walls with regular towers and gates. There were four gates, each protected by two pairs of quadrangular towers. The conveyor belt system consisted of a series of bridges connected by towers. The palace complex is entered through the symmetrical Gatehouse flanked by two stair towers. Nine of the fourteen Martello towers built in Canada still survive. Boasting elaborate stone carvings and eight of the twelve original towers. All but three of the towers are square in plan. Between them are two vertical office towers. It was constructed as part of a series of eight similar defensive towers. It is now the subject of a redevelopment project including the construction of twin towers. All but six of the towers were dismantled. Some of the face towers have collapsed.