Pharos Lighthouse

The Lighthouse of Alexandria, more commonly known as the Pharos Lighthouse, stood on an island in the harbour of Alexandria, Egypt. It was one of the Seven Wonders of the World. (PROSE: The Book of Shadows, The Ruby's Curse)

History
The Pharos Lighthouse was built in the 3rd century BCE (PROSE: The Ruby's Curse) during the reign of Ptolemy Philadelphus. (PROSE: The Book of Shadows) According to the Fourth Doctor, slaves were employed to keep its bonfires going. (TV: Horror of Fang Rock)

Like the other six Wonders, it was stolen by Pholonius Ginn, who intended on selling it to the highest bidder on G-Bay. It later returned by Trongus Squum, at the Tenth Doctor's request. (COMIC: Minus Seven Wonders)

The lighthouse was eventually destroyed by earthquakes. (PROSE: The Ruby's Curse)

Alternate timeline
In an alternate timeline, the First Doctor and Barbara Wright saw the Pharos Lighthouse in 322 BC. This was one of the clues that gave away the changes to history, as the lighthouse wasn't due to be built for some time, until after Ptolemy Lagus' death. The timeline was later reverted, with Barbara and the Doctor never landing in Egypt as a result. (PROSE: The Book of Shadows)