Aichelburg, Medieval castle near Pec pod Sněžkou, Czech Republic

Aichelburg, also called Hrádek, is a romantic structure on a rocky slope of the Světlá mountain above the Úpa river, less than a kilometre west of Temný Důl. It consists of a square stone lookout tower and an adjacent wooden building housing the castle hall, built over a preserved vaulted cellar.

Built in 1863 by the forest staff of the Maršov estate as a memorial to Count Berthold Aichelburg, who died in 1861, it was supervised by head forester Johann Miksch and opened on 9 September 1863. After the Černín-Morzin family bought the estate in 1883 the building was abandoned, its access paths vanished and the ceiling of the hall collapsed. The Hradní společnost Aichelburg, founded in 1996, restored it between 1998 and 1999 and reopened it in 2000.

The name honours Count Berthold Aichelburg, a Maršov estate owner remembered as a capable manager and patron of the eastern Krkonoše, who died in 1861. The forest staff built the Hrádek two years later, and the original bust of him, modelled by the Temný Důl glassmaker F. Hauptfleisch, was returned to the hall on 6 November 1999.

Aichelburg is reached on foot along the Aichelburg walking trail from Horní Maršov, through Temný Důl and the slope of Světlá via Velké Tippeltovy boudy, Vlašské boudy and Hlušiny; the route is marked by twenty-seven information panels. The Administration of the Krkonoše National Park restored two historic footpaths for this route. The wooden footbridge was replaced by a steel one after it collapsed under a group of wedding guests on 6 July 2010, injuring seven of seventeen people.

The wooden bridge at the castle collapsed on 6 July 2010 under a group of wedding guests posing for a photo; seven of the seventeen people were injured, and the bridge was replaced with a steel one.