Orel, Artillery fort in Darkovice, Czech Republic.

Orel is a Czech artillery fort in Darkovice with underground chambers connected by corridors. The installation consisted of several combat positions designed to house artillery pieces and machine guns.

Planned after Adolf Hitler became German chancellor, the fort was to be the easternmost of the Czechoslovak fortifications, sited between Darkovice and Darkovičky. Only the infantry casemate MO-S 20 "Orel" was actually built, begun by V. Nekvasil on 27 April 1936; the other five objects were never realized after the autumn of 1938.

The exhibition shows how soldiers lived and worked here, focusing on their daily tasks and the equipment they used. You can see how cramped the spaces were and how people moved through the underground passages.

Only the infantry blockhouse MO-S 20 "Aglo" was ever concreted; the mortar turret, artillery turret and entrance building were never built, so there is no underground system to walk through. The site lies near Darkovičky, about 4.5 km from Hlučín, and the surviving blockhouse is now part of the Hlučín-Darkovičky fortification museum.

The fort still has its original water filtration systems that were specially designed to protect against chemical weapons. These technical systems are rarely preserved so well in other forts from this era.