VENUE for 15 royal weddings, burial place of kings, place of worship for 670 years, St George's chapel is woven into our history.
The chapel is situated in the grounds of Windsor Castle - home to the Queen and Prince Philip for the majority of the year.
Harry and Meghan are following in the footsteps of Charles and Camilla, who got married there in 2005. Prince William and Kate Middleton tied the knot at Westminster Abbey.
Here's what you need to know about it, who's going to the wedding and what will happen at the ceremony.
Celebrities
Serena Williams, 36, tennis superstar. Became friends with Meghan in 2014 on Celebrity Beach Bowl, a US TV show.
Priyanka Chopra, 35, Indian actress, film producer, singer, winner of Miss World 2000, Meghan's friend.
Janina Gavankar, 37, Meghan's friend for 16 years, appeared with her in US sitcom The League.
The Spice Girls, Mel B told a US talk show that the 90s girl band were invited.
Millie Mackintosh, 28, Made In Chelsea star, Meghan's friend.
Page boys
Prince George, 4, Harry's nephew.
Jasper Dyer, 6, Harry's godson, son of Harry's mentor Mark Dyer, ex-Army officer and equerry to Prince Charles.
Brian and John Mulroney, 7, Twins of Meghan's friend Jessica Mulroney, a Canadian stylist.
Best man
Prince William, 35, Harry was William's best man in 2011.
Bridesmaids
Princess Charlotte, 3, Harry's niece.
Florence van Cutsem, 3, Harry's goddaughter, Daughter of friends Alice and Major Nicholas van Cutsem.
Zalie Warren, 2, Harry's goddaughter, Daughter of Jake Warren, son of Queen's racing manager and old school friend of Harry.
Remi and Rylan Litt, 6 and 7, Meghan's goddaughters, Children of best pal Benita.
Ivy Mulroney, 4, Daughter of Meghan's friend Jessica Mulroney, a Canadian stylist.
Royal Family
The Queen, Prince Philip, Prince Charles and the Duchess of Cornwall.
Kate Middleton, Duchess of Cambridge, Pippa Middleton and James Matthews, Kate's sister and brother-in-law.
Lady Jane Fellowes, Lady Sarah McCorquodale, Earl Spencer, Harry's aunts and uncle, Lady Jane will give a reading.
Duke of York Prince Andrew, Duchess of York Sarah Ferguson, Princesses Beatrice and Eugenie of York.
Duke and Duchess of Gloucester and the Duke and Duchess of Kent.
Prince Seeiso and Princess Mabereng of Lesotho, Co-founded charity Sentebale with Prince Harry in 2006.
The people
Amelia Thompson, 12, schoolgirl caught up in the Manchester terror attack.
Zoe Arundell, 20, volunteer at charity Valleys Kids in Tonypandy, South Wales.
Reuben Litherland, 14, deaf schoolboy and sign language teacher from Derby.
Rosie Ginday, 34, baking entrepreneur from Birmingham.
Pamela Anomneze, 52, from London, uses art to improve mental health.
Jorja Furze, 12, mental health charity helper from Ely, Cambs, born with one leg.
Philip 'Barney' Gillespie, 30, ex-soldier from Ballymena, lost a leg in Afghanistan, now raises funds for The Soldiers' Charity.
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Music and musicians
Before the service includes: Organ pieces by Bach, Vaughan Williams and orchestral pieces by Elgar, Holst and Hubert Parry. Played by organist Luke Bond and BBC National Orchestra of Wales, English Chamber Orchestra, The Philharmonia.
Hymns: Lord Of All Hopefulness, Guide Me O Thou Great Redeemer.
Song: Stand By Me by Karen Gibson and the Kingdom Choir.
Procession: Symphony No1 in B-flat-Allegro, William Boyce Amen (This Little Light Of Mine), Etta James version.
Other musicians: Cellist Sheku Kanneh-Mason, 2016 BBC Young Musician of the year, St George's Chapel choir The State
Trumpeteers Of The Household Cavalry, Harry's old regiment, Trumpeter David Blackadder, Soprano Elin Manahan Thomas.
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The Clergy
Service: Dean of Windsor the Rt Rev David Conner, Address: US Episcopal, Church bishop: the Most Rev Michael Curry, Vows: Archbishop of Canterbury Justin Welby.