Burgruine Falkenstein, Medieval spur castle in Obervellach, Austria.

Falkenstein Castle (Oberfalkenstein) is a ruined medieval spur castle above Obervellach in Carinthia, Austria, built in the 12th century. It formed part of a larger fortification complex together with the preserved advanced work of Niederfalkenstein below it on the slope.

The fortress was founded around 1127 to secure regional possessions and came under different rule throughout the centuries. It gained special importance when several noble families shared and jointly occupied the site.

The castle's name, Falkenstein, means "falcon rock", after the birds that gave the crag its name. The upper ruin is paired with the preserved lower stronghold, Niederfalkenstein, which served as its advanced work; the two together formed one fortification complex above Obervellach.

Access is gained through marked hiking trails in the surrounding forest, and sturdy footwear is recommended because of the steep terrain. It is wise to allow plenty of time and bring water, as the landscape is hilly and the site is remote.

In medieval times, the site was divided into three separate sections by transversal walls, allowing different noble families to live side by side. This arrangement shows a practical approach to sharing ownership of an expensive fortress.