Clifton Observatory and Caves, Bristol (must see)

The Clifton Observatory in Bristol is a historic site with a rich and fascinating history. The building, which is now used as an observatory, was originally erected in 1766 as a windmill for corn. It later became known as the Snuff Mill after being converted to the grinding of snuff. Unfortunately, it was damaged by fire in 1777 and remained derelict for over 50 years until it was rented by artist William West in 1828.

West transformed the old mill into a studio, installing telescopes and a camera obscura, which were used by artists of the Bristol School to draw the Avon Gorge and Leigh Woods. He called his photographic technique 'photogenic drawing' and it was based on the work of William Fox Talbot. Today, many examples of these paintings can be seen in the Bristol City Museum and Art Gallery.

The Observatory is now home to a 5 inches (13 cm) convex lens and sloping mirror which projects a panoramic view vertically downward into the darkened room below. Visitors can view the true image (not a mirror image) on a fixed circular table 5 feet (1.5 meters) in diameter with a concave metal surface and can turn the mirror by hand to change the direction of view. This unique attraction has been on top of Clifton Tower since 1828.

In addition to the observatory, West also built a tunnel from the Observatory to Saint Vincent's Cave (also known as Ghyston's Cave or Giants' Cave), which opens onto Saint Vincent's Rocks on the cliff face, 250 feet (76 meters) above the floor of the Avon gorge and 90 feet (27 meters) below the cliff top. The tunnel, which took two years to build, was first opened to the public in 1837.

Saint Vincent's Cave has an interesting history of its own. It was first mentioned as a chapel in AD 305 and has been used as a holy place and a place of refuge throughout history. Although the cave is in limestone, there are few formations in the natural passages.

The Clifton Observatory has been designated by English Heritage as a grade II* listed building and is on the Buildings at Risk Register.