Sacsayhuamán (also known as Saksaq Waman, Sacsahuaman or Saxahuaman) is a walled complex on the northern outskirts of the city of Cusco, Peru, the former capital of the Inca Empire. The complex is as many other Inca constructions made of large polished dry-stone walls, each boulder carefully cut to fit together tightly without mortar.
Predjama Castle is a Renaissance castle built within a cave mouth in southwestern Slovenia, located just 10 kilometres from Postojna. The castle was built under a natural rocky arch high in the stone wall to make access to it difficult.
Ollantaytambo, Peru The Incas built it as a fort that included a temple, agricultural terraces, and an urban area. There are two distinct sectors: Araqama Ayllu, the religious and worship zone, and Qosqo Ayllu, the residential area. Ollantaytambo was an important administrative center with probable military functions if one considers the walls and towers. There are also traces of ancient roads and aqueducts.