The British "Area 51" hides a maze of abandoned tunnels and "remains of alien spaceships" - voila! technology. The Royal Air Force's Rodolo Estate in Wiltshire was (apparently) Britain's official UFO investigation center in the 1950s.
The place is carefully preserved to this day, even though it has been abandoned for more than 23 years. Some believe the site contains clues about the Mount Berwyn UFO incident and the Randlesham Forest incident, known as "Britain's Roswell"