|"Is this all real? Or has this been happening inside my head?"
The subject of this article is a real-life person, company, product, or creative work that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
"The Spectral Thief of Old London Town"
In the early 17th century, wizard thief Eldon Elsrickle returned to London after having fled to Africa for a time to evade imprisonment. In Africa, he learnt about the Unlocking Charm (which was, at the time, an unheard of spell in the western world) from an ancient African sorcerer.
Elsrickle terrorised London with his new spell, burgling Muggle and wizarding homes alike. It was only when fellow Londoner Blagdon Blay invented the Anti-Alohomora Charm (in response to having his house broken-into nineteen times in the course of two weeks) that Londoners found safety again, and a frustrated Elsrickle stopped.
The Great Fire of London
The Great Fire of London was a major conflagration that swept through the central parts of the City of London, beginning on Sunday, 2 September, 1666. The Muggles say the Great Fire of London started in a bakery on Pudding Lane, but there is debate among the wizarding community whether it began in the bakery or in the basement of the house next door, where legend has it a young Welsh Green was being kept. 
In the late 19th century, the conditions on the relatively impoverished neighbourhoods of London worsened: robbery, violence, prostitution, social disturbance and alcohol dependency were commonplace.
As a climate of crime and fear flourished in the 1880s, Sir Herbert Varney, a vampire, started to prey on London women. He was eventually hunted down and killed by a specially-assigned task-force from the Department for the Regulation and Control of Magical Creatures. Around the same time, a Boggart, popularly known as the Bludgeoning Boggart of Old London Town, prowled the back streets of London and, feeding on people's fears, took on the form of a "murderous thug", before having been reduced to a hamster with one simple incantation — these two seem to account for the "serial killer" that Muggles dubbed "Jack the Ripper".
Caractacus Phelps's prank
On 1 April, 1979, Caractacus Phelps exploded no less than eight-hundred Stink Pellets, by dropping them en-masse from the roof of the Daily Prophet building in Diagon Alley. The resultant gas cloud caused untold discomfort throughout London, and approximately five-hundred cases of Stinkitus were reported. The Muggle authorities explained the stinking cloud away as an unpleasant emission from a nearby factory.
Second Wizarding War
London felt the effects of the Second Wizarding War severely. Many buildings and homes were destroyed or ransacked, and many people were attacked within the City during Lord Voldemort's rise of power: a crowded Millennium Bridge was brought down by a group of Death Eaters, Emmeline Vance was found dead near 10 Downing Street, Diagon Alley was attacked, leading to Garrick Ollivander's kidnapping and Florean Fortescue's murder.
London is an important city because it is where the Government of the whole United Kingdom is located. Some of its governmental locations include:
- 10 Downing Street  (the official residence and office of the Muggle Prime Minister of the United Kingdom)
- British Ministry of Magic Headquarters (main offices of the Ministry of Magic)
- Buckingham Palace 
- Sofie's office building  (a Muggle politician's offices, overlooking the Thames)
- Luchino Caffe
- A hamburger restaurant at Paddington Station 
- Chester Stevens Estate Agents  (a Muggle property management establishment)
- Diagon Alley  (a wizarding commercial street, including many shops)
- Gladrags Wizardwear (a wizarding clothing shop)
- John Kent Fruiterers  (a Muggle greengrocer's)
- Knockturn Alley  (a wizarding commercial street, including many shops dedicated to the Dark Arts)
- Pudding Lane's Bakery  (formerly)
- Screed & Sons
- The Leaky Cauldron  (a "portal between the two worlds", this inn was used to gain entrance to Diagon Alley)
- Third Hand Book Emporium  (a large bookshop)
London is the location of many important institutions, including:
- St Mungo's Hospital for Magical Maladies and Injuries (a wizarding hospital, concealed on a unused department shop)
- 12 Grimmauld Place (first used as the main residence of the House of Black; it was once used as headquarters of the Order of the Phoenix)
- Museum of Quidditch (a museum concerning the History of Quidditch)
- Society for the Tolerance of Vampires Head Office  (a candlelit office where STV matters are dealt with)
- Wool's Orphanage (formerly)
- King's Cross Station (a Muggle train station, where Platform 9 ¾ is hidden)
- Paddington Station  (a Muggle train station)
- Surbiton Station  (a Muggle train station)
- London Underground
- Millennium Bridge  (a pedestrian bridge over the Thames; destroyed in 1996)
- Library 
Behind the scenes
- London is a location that the films are often filmed in; the heart of London has been used in various scenes throughout the films, including taking Harry from his home to the Headquarters of the Order of the Phoenix, in which scene he and the others flew across the River Thames. The shots of the Millennium Bridge moments prior to its destruction were also filmed in London, on the real-life bridge.
- London has held premières of the films.
- The London Eye appears in the second part of the film adaptation of Harry Potter and the Deathly Hallows, in the year 1997 despite the fact that the wheel was only erected in 1999.
- Harry Potter and the Philosopher's Stone (First appearance)
- Harry Potter and the Philosopher's Stone (film)
- Harry Potter and the Philosopher's Stone (video game)
- Harry Potter and the Chamber of Secrets
- Harry Potter and the Chamber of Secrets (film)
- Harry Potter and the Chamber of Secrets (video game)
- Harry Potter and the Prisoner of Azkaban
- Harry Potter and the Prisoner of Azkaban (film)
- Harry Potter and the Prisoner of Azkaban (video game) (GBA version only)
- Harry Potter and the Goblet of Fire
- Harry Potter and the Order of the Phoenix
- Harry Potter and the Order of the Phoenix (film)
- Harry Potter and the Order of the Phoenix (video game)
- Harry Potter and the Half-Blood Prince
- Harry Potter and the Half-Blood Prince (film)
- Harry Potter and the Half-Blood Prince (video game)
- Harry Potter and the Deathly Hallows
- Harry Potter and the Deathly Hallows: Part 1
- Harry Potter and the Deathly Hallows: Part 1 (video game)
- Harry Potter and the Deathly Hallows: Part 2
- Harry Potter and the Deathly Hallows: Part 2 (video game)
- Harry Potter: A Pop-Up Book
- LEGO Harry Potter: Years 1-4
- LEGO Harry Potter: Years 5-7
- Pottermore (Mentioned only)
Notes and references
- ↑ 1.0 1.1 Wonderbook: Book of Spells
- ↑ 2.0 2.1 Fifth question of the third W.O.M.B.A.T. at J.K. Rowling's Official Site
- ↑ 19th century London, on Wikipedia
- ↑ Harry Potter and the Prisoner of Azkaban (video game) (Mentioned on a Famous Wizard Card)
- ↑ Pottermore - New from J.K. Rowling: "Boggart"
- ↑ Harry Potter and the Chamber of Secrets (video game) - GameCube/GameBoy Advance Link (Harry reads about this on a Hint Book, at Gringotts)
- ↑ 7.0 7.1 7.2 7.3 Harry Potter and the Half-Blood Prince (film)
- ↑ 8.0 8.1 8.2 Harry Potter and the Half-Blood Prince - Chapter 1 (The Other Minister)
- ↑ The Queen's Handbag
- ↑ 10.0 10.1 10.2 10.3 10.4 Harry Potter and the Philosopher's Stone - Chapter 5 (Diagon Alley)
- ↑ 11.0 11.1 Harry Potter and the Prisoner of Azkaban (film)
- ↑ Harry Potter and the Philosopher's Stone (film)
- ↑ Harry Potter and the Chamber of Secrets - Chapter 4 (At Flourish and Blotts)
- ↑ Daily Prophet Newsletters
- ↑ Harry Potter and the Deathly Hallows - Chapter 15 (The Goblin's Revenge)