Okiennik Wielki Rock Window

The Great Window, also known as the Large Window, - a group of limestone rocks, located in Piaseczno in the Kroczyce commune, in the Zawiercie district, in the Silesian voivodship. The most recognizable element of the group is a rock with a "window" - a rock opening measuring approx. 7 × 5 meters.
According to historians, around the 12th – 13th centuries, at the foot of the rocks, there was a fortified town with a wooden structure; traces of the walls were still visible in the 19th century. The rock with the rock window was a keep, the walls were reinforced with a rampart. The entrance led through a natural chimney in the rock. There is a carved hole in the rock window, which was probably used to fasten the structure made of wooden logs that covers the rock window.
In a natural cave below the window, archaeologists have found flint tools dating back about 60,000 years, i.e. the Middle Palaeolithic. They testify that the cave was then inhabited by prehistoric people. Archaeologists included them in the Mikocko-Prądnik culture.
pl.wikipedia.org/wiki/Okiennik_Wielki