An observatory is a location with equipment permanently mounted for the purpose of observing the sky and celestial events. Historically, these have been as simple as containing a sextant (for measuring the distance between stars) to as complex as Stonehenge (for measuring the seasons through the position of the sun's rising and setting). Modern day observatories typically contain one or more permanently mounted telescopes contained in buildings with a rotating or removeable dome. Within the last twenty years, many space-based observatories have been launched, introducing a new use of the term.
