Answer the following question: Bowmansville Roller Mill also known as the Von Nieda Mill is a historic roller mill and national historic district located at Bowmansville Brecknock Township in Lancaster County Pennsylvania. The district encompasses two contributing buildings and one contributing structure. The grist / roller mill was built in 1850 and is a 3 1/2-story rectangular brownstone building measuring 45 feet by 50 feet 5 inches. 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?
Answer:
Building