The last, the main, the largest, the most complex of Hitler's headquarters constructed in Lower Silesia.
The underground Complex of Osówka is situated just over a kilometre north-east of the village of Kolce, and at the same distance north of the village of Sierpnica.
Construction work commenced there in the summer of 1943. In time, a massive system of concrete passageways, reinforcements and halls was constructed. The objective of the project was kept secret. Some claim it was to become a secret headquarter of Adolf Hitler. Others maintain that these were to become workshops for an underground armament factory, where a secret weapon was to be manufactured. Most of the work was performed by the prisoners of the Gross-Rosen concentration camp.
The over-ground part of the Osówka Complex makes for the outer infrastructure of the underground facilities. The level of completion of the work makes the site the leader in the ranking of the most completed over-ground facilities of the "Riese" (German for a giant) project in the Sowie Mountains.
Of these, the most interesting are the tow objects, customarily named Kasyno (Casino) and Siłownia (Power Plant). The Kasyno is 50 metres long. It is equipped with window holes, a monolithic reinforced concrete roof, chimney ducts, installation pipes, as well as external heat insulation from chip-and-concrete boards. The ceiling was constructed in the form of a trough, which was to be filled with soil and plants at a later stage. Siłownia, on the other hand, is a concrete block consisting of containers and rooms, complete with steel-clamped hatch doors.
The Osówka Complex is located within the administration boundaries of the town of Głuszyca, in the District of Wałbrzych. It is considered to be the most interesting and the largest complex of that kind in the Sowie Mountains.