The Office of the President is located in Hopkins Hall, named after Mark Hopkins, Williams's fourth president, and the president of the college lives in the Samuel Sloan House, erected in 1801. Before moving into the Samuel Sloan House, the president originally lived in a nearby house where Hopkins Hall now stands. The house has been renovated multiple times since originally being built, including over $500,000 in renovations in 2000 and 2001. Since its creation in 1793, Williams College has had 17 full-time presidents and two interim presidents. The 18th President and current president is Maud Mandel, who began her tenure on July 1, 2018. Campus Williams is on a campus in Williamstown, Massachusetts in the Berkshires in rural northwestern Massachusetts. The campus contains more than 100 academic, athletic, and residential buildings. The early planners of Williams College eschewed the traditional collegiate quadrangle organization, choosing to freely site buildings among the hills. Later construction, including East and West Colleges and Griffin Hall, tended to cluster around Main Street in Williamstown. The first campus quadrangle was formed with East College, South College, and the Hopkins Observatory. The Olmsted Brothers design firm played a large part in shaping the campus design and architecture. In 1902, the firm was commissioned to renovate a large part of campus, including the President's House, the cemetery, and South College; as well as incorporating the George A. Cluett estate into the campus acreage. Although these campus renovations were completed in 1912, the Olmsted Brothers would advise the gradual transformation of campus design for six decades. The present-day grounds layout reflects much of the design intent of the Olmsted Brothers. Williams College is the site of the Hopkins Observatory, the oldest extant astronomical observatory in the United States. Erected in 1836–1838, it now contains the Mehlin Museum of Astronomy, including Alvan Clark's first telescope (from 1852), as well as the Milham Planetarium, which uses a Zeiss Skymaster ZKP3/B optomechanical projector and an Ansible digital projector, both installed in 2005. The Hopkins Observatory's 0.6-m DFM reflecting telescope (1991) is installed elsewhere on the campus. Williams joins with Wellesley, Wesleyan, Middlebury, Colgate, Vassar, Swarthmore, and Haverford/Bryn Mawr to form the Keck Northeast Astronomy Consortium, sponsored for over a decade by the Keck Foundation and now with its student research programs sponsored by the National Science Foundation. Hopkins Hall serves as the administration building on campus, housing the offices of the