By Roberta Rampton and Alex Fraser
LONDON/STRATFORD-UPON-AVON, England (Reuters) - U.S. President Barack Obama marked the 400th anniversary of Shakespeare's death on Saturday by visiting the Globe theatre in London for a performance of a scene from Hamlet, where the Danish prince poses the question: "To be or not to be".
Celebrations were also underway in Stratford-upon-Avon where England's greatest playwright was born in 1564 and died in 1616.
Thousands of people lined the streets of half-timbered Tudor buildings in the Warwickshire market town, 100 miles northwest of London, and donned Shakespeare masks to watch a procession of characters from the playwright's comedies and tragedies.
On the banks of the Thames, actors at The Globe, London's monument to the Bard, treated Obama to a preview of a special touring production of his tragedy Hamlet, which was due to be performed there later on Saturday.
As the sun illuminated the theatre's wooden stage through the open roof, Obama was entertained for 10 minutes by a troupe of actors playing violins, mandolins, an accordion and penny whistles.
"That was wonderful. I don't want it to stop," Obama said.
The visit was something of a pilgrimage for the 44th President of the United States who has named Shakespeare's tragedies as among the top three books that have inspired him.
With its white-washed curved walls, the Globe opened in 1997 and is a replica of a theatre where Shakespeare performed, situated a few hundred yards from today's version, which burned to the ground in 1613.
Performances of Hamlet and the Bard's other plays were also on the agenda in Stratford, where street artists in Elizabethan costumes erupted into verse, including a group who had travelled from Kentucky, in the United States, to set up stage outside the house where Shakespeare was born.
Britain's Prince Charles and his wife Camilla are set to join the celebrations later on Saturday when they attend a performance in the Royal Shakespeare Theatre in Stratford.
For the actors watched by Obama in Hamlet, the celebrations of the Bard's life started two-years ago, when they embarked on a tour which has performed in 189 countries.
As well as the home-coming of the Hamlet tour, the anniversary was also marked in London by a series of screens along the River Thames which showed short films of each of Shakespeare's 37 plays.
British Prime Minister David Cameron said Shakespeare's genius had captivated and changed the world.
"His words about this nation 'this precious stone set in the silver sea' remain as potent as the day he wrote them," Cameron said, quoting from Richard II.
Ian Waterhouse, in Stratford to take part in the parade, agreed with the Prime Minister.
"Science and technology moves on. Nature moves on and morphs. We don't. We actually have all the angst, the love and the fear - everything that goes with Shakespeare and what came out of that time is still relevant to every single person alive and here today," he said.