Brindisi di Montagna Castle was built around 1200 and is situated on a large rocky ridge. The architecture is characterized by three main elements: The central part (a long the rocky ridge of the hill).The northern part, with the turret for lookout (later transformed by the Antinori family into the chapel of San Michele) and the southern part where there are few but significant wall traces embedded in the rocky elements.
Its defensive function is evident both from the presence of arrow slits and its position overlooking the intersection of the two routes leading to the fortress. It differs from the Swabian castles in terms of its layout, formal characteristics, and construction techniques, as it predates others built by Frederick II. Instead, it has undergone numerous transformations since the Angevin rule.
Celje Castle was once the largest fortification on Slovenian territory. The first fortified building on the site (a Romanesque palace) was built in the first half of the 13th century by the Counts of Heunburg from Carinthia on the stony outcrop on the western side of the ridge where the castle stands. It had five sides, or four plus the southern side, which was a natural defence. The first written records of the castle date back to between 1125 and 1137; it was probably built by Count Gunter. In the western section of the castle, there was a building with several floors. Remains of the walls of this palatium have survived. In the eastern section, there was an enclosed courtyard with large water reservoirs. The eastern wall, which protects the castle from its most exposed side, was around three metres thicker than the rest of the curtain wall. The wall was topped with a parapet and protected walkway.