The campus of Northwestern University encompasses two campuses in Evanston, Illinois and Chicago, Illinois, United States. The original Evanston campus has witnessed approximately 150 buildings rise on its 240 acres (0.97 km2) since the first building opened in 1855. The downtown Chicago campus of approximately 25 acres (100,000 m2) is home to the schools of medicine and law was purchased and constructed in the 1920s and 1930s.