This Week in Photos, Week of May 20-26, 2011

A farmer carries grass to feed water buffaloes in Sapa, northwest Vietnam.

US President Barack Obama reviews an honour guard with Prince Philip, Duke of Edinburgh at Buckingham Palace in London, England. The 44th President of the United States, Barack Obama, and his wife Michelle are in the UK for a two day State Visit at the invitation of HM Queen Elizabeth II. During the trip they will attend a state banquet at Buckingham Palace and the President will address both houses of parliament at Westminster Hall.

Mohammad Alishan, a performer from India's eastern state of Jharkhand, performs a stunt as he drives a car on the walls of a "Well of Death" at a fair in Srinagar. The performers earn their livelihood by performing daredevil stunts by driving their bikes and cars on the walls of the "Well of Death" and attract a large number of spectators from all walks of life.

A plane flies past smoke plume from the eruption of the Grimsvotn volcano, under the Vatnajokull glacier in southeast Iceland. Airlines began cancelling flights to Britain late on Monday because of an ash cloud from an Icelandic volcano reaching its airspace, although experts expected no repeat of travel chaos from an eruption a year ago.

Jockeys ride their horses at the beginning of a race in the Greek hippodrome, southeast of Athens. Greece has pledged to its EU partners to target 50 billion euros ($70 billion) from privatisations and real estate assets, including the Hellenic horse racing company (ODIE), by 2015 to help reduce its debt.

A boy runs in front of the skyline after a rain storm in Toronto.

A man and a child stand near a rocket system at the MILEX-2011 arms and military equipment exhibition in Minsk. Several countries from the former Soviet Union took part in the MILEX-2011 arms and defence technology exhibition that opened on Tuesday.

Hong Kong businessman William Louey poses in his floral hat during media day at the Chelsea Flower Show 2011, London.

The "Plastic Bag Monster", a creation by Slovenian artist Miha Artnak, is displayed outside the European Commission headquarters in Brussels. Artnak collected 40,000 used plastic bags and 7,500 used plastic cups to create the "Plastic Bag Monster" artwork, which symbolizes the spread of consumerism and waste segregation, according the the artist's website.

Dancers of Pilobolus Dance Theatre perform during a rehearsal of "Metamorphosis" in Sao Paulo. The performance will run from May 24 to 25.

Pujie Girls, Karren (L) and Jinyu, pose for a photograph while demonstrating planking during an interview with Reuters at Ximending in Taipei. Lying face flat on the ground may not be the world's most glamourous photo pose but two Taiwanese "planking" women have made a name for themselves on the Internet -- and hope to use the craze to spread positive social messages. Calling themselves the Pujie Girls which literally translates to "falling on the street" in Mandarin, the pair are Taiwan's most well-known plankers, with almost 100,000 fans following them on Facebook.