Ostra horka, Observation tower in Soběšice, Czech Republic

Ostrá horka is a metal observation tower on the hill of the same name in Soběšice, Brno. It is 19.1 m high, has two observation decks at 8 m and 16 m, and a spiral staircase with 90 steps. It opened on 1 June 2008.

The metal lookout tower on Ostrá horka opened on 1 June 2008. The site had earlier held the St. Cross Chapel, built in 1718 and demolished in 1786; in 1759 the cartographer Josef Liesganig placed the first trigonometric point of the Habsburg lands here, on the chapel. A granite block with two plaques now marks the spot.

The hill's name, Ostrá horka, means "sharp hill". A granite block beside the tower marks the first trigonometric point of the Vienna meridian network, surveyed by Josef Liesganig in 1759; its plaques recall the St. Cross Chapel that stood here from 1718 until its demolition in 1786.

The tower stands on Ostrá horka hill in Soběšice; the nearest bus stop is "Soběšice, Ostrá horka", and a parking lot serves drivers. Inside, a spiral staircase of 90 steps leads to two decks, at 8 m and 16 m.

The granite block beside the tower marks the first trigonometric point on Czech territory, measured by Josef Liesganig in 1759; it stands 110 cm above ground and bears two plaques, one recalling the St. Cross Chapel demolished in 1784.