Sion Castle, Gothic castle ruin in Chlístovice, Czech Republic.

Sion Castle is a ruin on a steep rock above the right bank of the Vrchlice, about one kilometre east of Chlístovice. It was a small triangular castle with a small outer ward protected by an earth rampart, a deep ditch and a small semicircular tower that could hold cannon. Only foundation walls overgrown with shrubs remain.

The castle was founded between 1426 and 1427 by Jan Roháč of Dubá as a stronghold during religious conflicts. It was destroyed in 1437 after a four-month siege by Emperor Sigismund's forces.

The castle's name comes from the biblical Zion. After 1437 the site passed to King Sigismund and later owners; a 1677 visit by Bohuslav Balbín recorded that perimeter walls still stood. The ruin was quarried for stone under the Ostein owners, and in 1870 Karel Dahlberg-Ostein had the last large remains removed.

The site is accessible from Kutná Hora and can be reached on foot, so wear sturdy shoes and allow time for the climb to the hilltop. Since the castle sits away from main roads, it helps to plan your route beforehand for the best access path.

The castle had no well of its own, and during the 1437 siege the garrison is thought to have drawn water from the nearby Vrchlice stream. Archaeological digs in 1962–1965 found about 100 stone balls but no traces of mines or a breach in the walls.