Sasso Corbaro, known as Unterwalden Castle after 1506 and Saint Barbara's Castle after 1818, is about 600 m south-east of town on a rocky hill. Unlike the other two castles Sasso Corbaro is not integrated into the city walls. The first part of the castle was the north-eastern tower which was built in 1478 to close a gap in the defenses of the city. In 1479 a small garrison was moved to the tower. During peacetime the tower was used as a prison, though at least one prisoner escaped in 1494. The walls and south-west tower were added later. The castle was struck by lightning multiple times during the 16th and 17th centuries, and by 1900 was falling into ruins.
The fortress is a 25 by 25 m square with square towers on the north-east and south-west corners. The east wall is 1.8 m thick and other walls are about 1m thick. All the walls have machicolations and swallowtail merlons for defense. The entrance to the courtyard is through the western wall, and contains evidence of a portcullis. The two story buildings on the south and west walls were both living quarters with a gabled roof. The castle chapel is located on the eastern side of the courtyard.
The north-eastern keep currently has four stories, though no records exist of its original height and roof. It was used as a living area when the castle was occupied.
Today, Sasso Corbaro Castle houses the Sala Emma Poglia which is the 'wooden room' built for the Emma family during the 17th century. Originally located in the entrance hall of their home in Olivone in the Blenio Valley, the room was purchased by the Canton of Ticino in 1944 and housed first in Castelgrande before being moved to the Sasso Corbaro in 1989. The room is panelled entirely in walnut and also includes the stüva, stove which provided heating. The stove bears the crest of the Emma family (an eagle and a lion rampant). The museum also houses temporary exhibits. It is open from March until November.References:
Roman Walls of Lugo are an exceptional architectural, archaeological and constructive legacy of Roman engineering, dating from the 3rd and 4th centuries AD. The Walls are built of internal and external stone facings of slate with some granite, with a core filling of a conglomerate of slate slabs and worked stone pieces from Roman buildings, interlocked with lime mortar.
Their total length of 2117 m in the shape of an oblong rectangle occupies an area of 1.68 ha. Their height varies between 8 and 10 m, with a width of 4.2 m, reaching 7 m in some specific points. The walls still contain 85 external towers, 10 gates (five of which are original and five that were opened in modern times), four staircases and two ramps providing access to the walkway along the top of the walls, one of which is internal and the other external. Each tower contained access stairs leading from the intervallum to the wall walk of town wall, of which a total of 21 have been discovered to date.
The defences of Lugo are the most complete and best preserved example of Roman military architecture in the Western Roman Empire.
Despite the renovation work carried out, the walls conserve their original layout and the construction features associated with their defensive purpose, with walls, battlements, towers, fortifications, both modern and original gates and stairways, and a moat.
Since they were built, the walls have defined the layout and growth of the city, which was declared a Historical-Artistic Ensemble in 1973, forming a part of it and becoming an emblematic structure that can be freely accessed to walk along. The local inhabitants and visitors alike have used them as an area for enjoyment and as a part of urban life for centuries.
The fortifications were added to UNESCO"s World Heritage List in late 2000 and are a popular tourist attraction.