North of Smolenice is the village Buková with water reservoir and a marked route, which leads southward to the romantic ruins of the Castle Ostrý Kameň from the 13th century. The Castle was a royal border fort guarding the Czech road in the past. It is in decay since the 18th century though part of its walls, bastion, and adjacent buildings are still observable. The top of the Castle provides a nice view of the Malé Karpaty Mts. and the Záhorská nížina lowland.
References:The city walls of Avila were built in the 11th century to protect the citizens from the Moors. They have been well maintained throughout the centuries and are now a major tourist attraction as well as a UNESCO World Heritage Site. Visitors can walk around about half of the length of the walls.
The layout of the city is an even quadrilateral with a perimeter of 2,516 m. Its walls, which consist in part of stones already used in earlier constructions, have an average thickness of 3 m. Access to the city is afforded by nine gates of different periods; twin 20 m high towers, linked by a semi-circular arch, flank the oldest ones, Puerta de San Vicente and Puerta del Alcázar.