|"Is this all real? Or has this been happening inside my head?"
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The Millennium Bridge was a pedestrian suspension bridge that crossed the River Thames in London. It was built some time before the Summer of 1995 and destroyed by Fenrir Greyback and a small group of Death Eaters in early July of 1996. 
In the summer of 1996, Lord Voldemort ordered Cornelius Fudge to step aside from his position as Minister for Magic, with the threat of a mass Muggle killing if he did not do so.  Fudge refused to step down, and thus Voldemort ordered Death Eaters to cause the Brockdale Bridge  and the Millennium Bridge to collapse.  In early July, 1996, the bridge was attacked by Fenrir Greyback and a group of Death Eaters.  The cables snapping, the bridge undulated and twisted intensely, pulling free of its piers, ultimately splitting in half and crashing violently into the Thames below, killing about 50 Muggles who were crossing the bridge at the time. 
The collapse of the Millennium Bridge had serious consequences in both the Muggle world and Wizarding world. Shortly after it, a police investigation took place and river traffic was halted while the police searched for survivors of the disaster. The Mayor of London spoke to the population, urging them to be calm. The collapse of the Millennium Bridge was most likely also a contributing factor for the replacement of Cornelius Fudge by Rufus Scrimgeour in the post of Minister for Magic.  The attack was reported in tabloids such as The Sun and The Daily Mail.
Behind the scenes
- The Millennium Bridge, located in London, was used in place of the Brockdale Bridge in the film adaptation of Harry Potter and the Half-Blood Prince. Despite its representation, the collapse shown is not to be confused with the Brockdale Bridge's collapse that occurs in the book.
- The newspaper says that the collapse of the bridge raised the death toll but it seems like everyone got off the bridge before the collapse.
- The real-life Millennium Bridge had not begun construction in 1996 but in fact started in late 1998, with the main work starting on 28 April 1999.
- Harry Potter and the Philosopher's Stone (film) (First appearance)
- Harry Potter and the Order of the Phoenix (film)
- Harry Potter and the Half-Blood Prince (film) (First identified as Millennium Bridge)
- Harry Potter and the Half-Blood Prince (video game)
- LEGO Harry Potter: Years 5-7
Notes and references
- ↑ LEGO Harry Potter: Years 5-7
- ↑ Although the actual Millennium Bridge was built in 2000 and still stands today, the in-universe Millennium Bridge was built before 1996 and collapsed in July 1996.
- ↑ 3.0 3.1 3.2 Harry Potter and the Half-Blood Prince - Chapter 1 (The Other Minister)
- ↑ 4.0 4.1 Harry Potter and the Half-Blood Prince (film) - Chapter 1
- ↑ Inside the New Harry Potter Movie's VFX Tech at Popular Mechanics.
- ↑ In Harry Potter and the Half-Blood Prince (film), a headline on the Daily Prophet is visible stating: "Bridge Collapse: Death Toll Rises"