Untere Burg (Lower Castle) also known colloquially as Burg Alt-Schellenberg (Castle of Alt-Schellenberg) is a castle ruin located in the municipality of Schellenberg Liechtenstein. It lies at the edge of a local forest a few hundred meters north of the main road between Vorderer Schellenberg and Mittleler Schellenberg (two of the burroughs in the village of Alt-Schellenberg). It is freely open to tourists and accessible by foot or mountain bike via a local footpath. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
Building