Landsee castle ruins, Medieval castle ruins in Markt Sankt Martin, Austria

Landsee castle ruins stand on a rocky spur at 537 metres in Markt Sankt Martin, Burgenland, covering about 300 by 200 metres. Four rings of fortification, the first separated by two ditches, lead through six gates to the central building; the residential tower's walls are up to ten metres thick. The tallest element is a cylindrical stone tower with a flat, overgrown top.

The castle was first recorded in 1173 with Erchenger von Landesehre, and by 1222 it belonged to Hungary. Duke Albert of Austria captured it in 1289 during the Güssing Feud. In 1612 it passed to Nikolaus Esterházy; fires in 1707 and 1790 led to its abandonment, and from 1802 it served as a quarry. Since 1968 it has been secured and opened to the public.

The name Landsee has no link to a lake: it derives from the Hungarian Lánzsér, from an old German form Landeshere, and Lánzsér is also translated as "lance bearer". The castle's first chapel stood in one of the towers attached to the donjon; a new staircase now leads from there up to the former roof area of the donjon, where a free-standing masonry arch remains.

The grounds are accessible during warmer months and work well for walking and exploring at your own pace. It helps to wear sturdy shoes since the terrain is uneven and steps lead through the ruins.

The castle's name has nothing to do with a lake: it derives from the Hungarian "Lánzsér", itself from an originally German "Landeshere", also translated as "Lanzenträger" (lance bearer). The "hehr" element marks it as a once highly esteemed stronghold, a formation similar to Landskron.