Here's a schedule of performance times so you can plan your weekend.
The nominations for the most prestigious awards in the UK theatre calendar have been revealed today.
The websites drew complaints that advertised prices were misleading
The Apollo Theatre will reopen today three months after a ceiling collapse injured 76 people. A chunk of plaster crashed in the audience during violent thunder storms in December 2013. The theatre has been closed since the incident.
Originally home to the production of The Curious Incident of the Dog in the Night Time, the Apollo will now show romantic horror Let the Right One In. The opening today will be the debut of a production by the National Theatre of Scotland
Stars of the London stage will come together this afternoon for carol singing and festive merry-making in support of this year's Lord Mayor of Westminster's charity, the Sir Simon Milton Foundation.
The carol singing will be led by the West End Gospel Choir, a collective of musical theatre singers who will perform a selection of festive songs.
There will be a live performance from the cast of hit musical Let It Be as well as special appearances from family shows The Snowman and Dinosaur Zoo.
The show kicks off in Leicester Square at 4pm.
A rescue operation is under way after part of a balcony in the Apollo theatre in central London is thought to have collapsed during a performance, trapping people inside, according to eye-witnesses.
More details to follow.
Helen Mirren and Billie Piper are both up for the Natasha Richardson Award for Best Actress at tonight's Evening Standard Theatre Awards.
Helen, who has already won an Oscar for playing the Queen, competes for her role as the monarch in The Audience.
Billie, shortlisted before in 2007, makes the final five this year for her role in The Effect, as a troubled young woman participating in a clinical drugs trial.
Kristin Scott Thomas, Lesley Manville and Linda Bassett are also up for the gong.
Damien Lewis will host the event at the Savoy Hotel tonight.
Tens of thousands of people have watched some of their all time favourite musicals today for free.
From Matilda to Wicked - 30 West End productions are being showcased in the heart of the capital all weekend. Phil Bayles got a sample of the action.
-It's the largest event of its type in the UK and thousands of people are expected to visit central London to see West End performances for free all weekend.
-Performances are programmed on stage 11am-6pm on Sat and 12pm-6pm on Sun.
-Entry is on a first come, first served basis.
Stars of the West End will gather in Trafalgar Square this weekend for the annual theatre and musical festival West End LIVE – a weekend of free entertainment from London’s topshows and the largest event of its type in the UK.
More than half a million people are expected to gather for live performances from West End favourites like Billy Elliot The Musical, Jersey Boys, Disney’s The Lion King, Mamma Mia!, Matilda The Musical, Les Misérables, The Phantom of the Opera, War Horse and Wicked.
There will also be an exclusive preview of new musical From Here To Eternity on Saturday introduced by the legendary lyricist Sir Tim Rice.
Lucrezia Millarini outlines the runners and riders at this year's Olivier Awards - the most prestigious prizes in British theatre.