Please answer the following question: List of subcamps of Mittelbau - The list of subcamps of Mittelbau identifies locations of Konzentrationslager (English: concentration camp) Mittelbau (Central Construction). The location of the KZ Mittelbau headquarters was originally only the Block 17/3 Buchenwald subcamp but at the end of September 1944 the SS administration ordered the camp to become the center of a complex separate from the Buchenwald concentration camp. Given a choice of categories company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, the text refers to which one?
A:
Building