Observatory House was an observatory in Slough, England. It was built, run and used by the astronomer William Herschel, and his sister Caroline. The famous '40-foot telescope' - at that time the largest in the world - was housed there in the late 18th century and early 19th century. A monument to Herschel was erected in 1969 outside Observatory House on Herschel Street, close to where the 40-foot telescope was located. It was designed by the Czech sculptor Franta Belsky.