The Belogradchik Fortress (Bulgarian: Белоградчишка крепост, Belogradchishka krepost), also known as Kaleto (Калето, "the fortress" from Turkish kale), is an ancient fortress located on the north slopes of the Balkan Mountains(Old Mountain), close to the northwestern Bulgarian town of Belogradchik and is the town's primary cultural and historical tourist attraction, drawing, together with the Belogradchik Rocks, the main flow of tourists into the region.

The Bulgarian tsar of Vidin, Ivan Stratsimir extended the old fortress in the 14th century, building fortified garrisons in front of the existing rock massifs.

They were forced to further expand the stronghold due to the intensified hajduk and insurrectionist activity in the region.

These changes were typical for the Ottoman castle architecture of the period, a full reorganization being carried out, as well as additional expansion.

Typically European elements were added to the Belogradchik Fortress owing to the French and Italian engineers that participated in the expansion.