Old Castle, Monument of local significance in Zagrad pri Otočcu, Slovenia.

The Old Castle stands on elevated ground in Zagrad pri Otočcu and features sturdy stone walls that reflect medieval construction techniques. The ruins reveal foundations and wall sections that show how the structure was once organized and used.

First mentioned in 1251 as Altenburg, the castle was built by the Patriarchs of Aquileia as their easternmost outpost. Held by the knights of Stari grad, it passed to the Ortenburgs in 1350, the Counts of Celje in 1418 and the Habsburgs in 1456. After 1617 it changed owners rapidly; in 1806 it came to the Margheri de Commandona counts, who in 1931 gave it to the Mercy Brothers' convent in Novo mesto. Burned during the war, it now belongs to the Krka factory, which is gradually restoring it.

The name Altenburg, first recorded in 1251, likely refers to the newer castle at Otočec. Local legends explain the walls: the giant Samson supposedly built the castle before Christ using seawater, which is why the masonry is still so strong. A field below the castle is called "Na krivici" after peasants forced to pull the plough. A chapel of the Mother of God stood at the entrance until the fire, and castle chaplains served from 1692 to 1773.

The castle stands in Zagrad pri Otočcu, on the southern slope of Trška gora, and has been under renovation for years, so parts of the building may be closed off. The nearby settlement of Šentpeter (Otočec) is the usual starting point for the climb. Sturdy shoes help on the uneven slope.

The structure occupies an elevated position that offers views across the surrounding landscape and allows visitors to see far into the valley below. This viewpoint quality makes it a key location for understanding how earlier settlements related to the geography of the area.