The remains of the Castle can be visited
Grafenberg Castle (Ruin) (Maienfeld)

West above the connecting road from Maienfeld to Balzers in the canton of Graubünden is the Grafenberg ruin, also known as Mörderburg (Murderer's Castle). This former castle complex, whose origins are presumed to be in the 13th century, shows visible remains of a fortress.
History+
The exact history of the Grafenberg Castle's construction is not documented in written records. However, clues such as masonry in opus spicatum and fragments of stove tiles suggest its erection in the 13th century. The name Grafenberg first appeared around 1579, while the designation Mörderburg is already attested in 1498 and could point to a legend of robber knights or a hostile relationship with the castle lords. In the Swabian War of 1499, an associated Letzi (defensive wall) was stormed by imperial troops and later recaptured by the Bündner. Burned debris inside the ruin indicates destruction by fire.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 47.0461, 9.5130