A popular tourist destination is Súľov Castle, which is considered the most inaccessible castle in the Považie region, as its ruins stand at an elevation of 660 m above sea level. The complex structure was built into the rocky terrain, which makes it a very valuable and interesting
technical and architectural monument. Based on its position, the castle was called the “eagle’s nest” and, depending on the method of construction, also the “swallow’s nest”. The exact start of the castle’s construction is unknown. The first written mention of the castle dates back to 1470, when the building already existed on a smaller scale, and when the Hungarian King Matthias Corvinus allowed Eliaš Suľovsky to reinforce and expand the castle or fortress with walls, towers, ramparts and ditches in the style of a castle. In the 16th century, members of the Podmanicky family from Bystrica Castle consolidated their power in the Považie region. They, too, were interested in Suľov Castle; therefore, they did not agree with the decision of King Ferdinand I of Habsburg to grant it to Sebastian Sirmiensis. As a sign of his protest, Raffael Podmanicky set fire to the castle in three places during the ceremonial handover of the property to the new owners on 29 December 1550, and he did so in the presence of invited nobility, neighbours and other important guests. The castle comprised two parts – the upper and lower castles – which were connected by a tunnel corridor carved into the rock. The upper castle contained a water cistern 3 m deep as well as an observation tower and representative and residential areas. It also had a kitchen, a bakery, a study, a grain and flour warehouse, an armoury, stables, a treasury with family archives and cellars. The original access road was different from the current entrance to the castle, leading instead from the south side. In his work on the Trenčín County, Matej Bel wrote that the gate leading into Suľov Castle was carved into a rock cliff and had a high wooden drawbridge, which was not even as high as the depth below it. In 1759, the castle owners no longer lived in the castle but instead resided in manor houses beneath the castle. In 1763, the castle was significantly damaged by an earthquake whose epicentre was in Komarno, and in 1858 by another centred in Žilina.
In 1780, the castle was no longer guarded, and it has remained abandoned and dilapidated for centuries. Only a handful of disjointed walls and foundations cut into the rock have survived from the original structure. Unfortunately, Matej Bel already referred to the castle as a ruin in the mid-18th century, and Alexander Lombardini in the second half of the 19th century stated that the remains of the castle were difficult to distinguish from the village with the naked eye. Suľov Castle became a National Cultural Monument in 1963.