The Apollo Theatre is a Grade II listed building in London's West End.
Designed by architect Lewin Sharp for owner Henry Lowenfield, it was completed in February 1901 and was the fourth legitimate theatre to be constructed in Shaftesbury Avenue.
As the first London theatre built in the Edwardian period, the Apollo was renovated by Schaufelberg in 1932, and a private foyer and anteroom was installed to the Royal Box.
The theatre seats 755, and the balcony on the third tier is considered the steepest in London. It is not known whether it was this one which collapsed.
The Stoll Moss Group bought it in 1975 and sold it to Andrew Lloyd Webber's Really Useful Group and Bridgepoint Capital in 2000.
Nica Burns and Max Weitzenhoffer then bought it with several others in 2005, creating Nimax Theatres, which still owns the Apollo.
It has played host to a number of performances and a range of world-famous acting talent has appeared throughout its history. It opened with a selection of Edwardian musical comedies and light operas.
From the 1970s to the 1990s, the theatre staged performances featuring actors including John Mills, Vanessa Redgrave, Zoe Wanamaker, Peter O'Toole and Penelope Keith.
More recent productions have included roles by Rosamund Pike in Summer And Smoke (2006), Jessica Lange in The Glass Menagerie (2007), Josh Hartnett in Rain Man (2008) and James McAvoy in Rain (2009).
More recently, it hosted David Suchet in Eugene O'Neill's Long Day's Journey Into Night and productions of Shakespeare's Twelfth Night and Richard III starring Mark Rylance.
The accident happened during a performance of The Curious Incident Of The Dog In The Night-Time, which has been running in London since August 2012.
Winner of a record-breaking seven Olivier Awards - including Best Play - the show started at The National Theatre, before transferring to the Apollo in March.
The production is based on Mark Haddon's award-winning novel, adapted by Simon Stephens and directed by Marianne Elliott.