Nelson's Column

Nelson's Column was a monument in Trafalgar Square, London, consisting of a tall column with a statue situated on top.

History
On 23 October 1843, the Fifth Doctor climbed the column and confronted two Sevakrill who had taken over the bodies of the column's builders: Samuel Morton Peto and Thomas Grissell.

They had built a missile inside the column and planned to detonate it in 2017, destroying the Earth and distracting the Charnal horde, with whom they were at war. To protect this operation, they had several stone lions, hidden by perception filters, patrol the area. The Doctor managed to appeal to Peto and Grissell and they broke free.

The Doctor spent two weeks lowering the missile into a shaft beneath the column and building a floor to cover it. By this time it was November, and the statue of Nelson was being added when the Doctor departed. (PROSE: The Lions of Trafalgar)

Barbara Wright and Ian Chesterton climbed about the Column and its lions when sightseeing upon their return to London in 1965. (TV: The Chase)

The Seventh Doctor materialised his TARDIS around Nelson's Column in 1976. The Monk caused the Doctor's TARDIS to change its appearance from that of the column to that of the Statue of Liberty. (PROSE: No Future)

The Eleventh Doctor visited Nelson's Column with Amy and Rory in 2012. He stated that one of the four plinths was empty because there had not been enough money to put a statue on it. Amy believed that they had been showing works of art on the empty plinth and changing them out every year or two. The Doctor believed they were looking for a permanent piece of art for the space. (PROSE: Magic of the Angels)

Around the 2010s, Nelson's Column was toppled by a forest that grew overnight. As it fell, it almost crushed the Twelfth Doctor and Clara Oswald and broke the statue of Nelson. (TV: In the Forest of the Night)

By the late 21st century, a T-Mat cubicle was installed in Trafalgar Square, just north of Nelson's Column. (TV: The Seeds of Death)

Around 2167, a Dalek patrol passed the column while chasing Barbara Wright, Dortmun and Jenny. (TV: The Dalek Invasion of Earth)

Alternate timelines
In an alternate timeline, Nelson's Column was destroyed by the Daleks when they invaded Earth in 1903. After the invasion was defeated, it was replaced by the English Empire with Doctor's Column, a statue of the Sixth Doctor, who had aided in their victory. (AUDIO: Jubilee)

In a timeline where the Daleks exterminated humanity in 1963, Nelson's Column, along with London and presumably the rest of the world, was in ruins. When the Eleventh Doctor and Amy Pond arrived in the Square in 1963, the Doctor's TARDIS landed next to the statue's toppled head. The timeline was restored when the TARDIS crew travelled to Skaro to destroy the Eye of Time. (GAME: City of the Daleks)

Minor references
The Ninth Doctor mentioned that an alien spaceship could be placed in front of Nelson's Column, and humans would just walk around it. Rose Tyler responded that she was there when he did it. (COMIC: The Love Invasion)

Behind the scenes
It was suggested that the top of Nelson's Column should be seen sticking out of the landscape of the future Earth in The Sontaran Experiment, but the idea was dropped for reasons of cost.