Police guard Polio vaccination team, during a three-day vaccination campaign in Karachi, Pakistan, 24 May 2016

Shahzaib Akber/EPA

Police guard a polio vaccination team, during a three-day vaccination campaign in Karachi. Pakistan. Though new polio cases dropped to a nine-year low in 2015, attacks by Islamist militants against health workers and police guarding them remained a challenge for a UN-funded vaccination campaign.

A Bahraini man takes pictures with his mobile phone as great crested terns (aka sterna bergii) fly over their nests during the breeding season on May 20, 2016 on Fasht al Jarim Island, north of the Bahraini capital Manama

Mohammed Al-Shaikh/AFP/Getty Images

A Bahraini man takes pictures with his mobile phone as great crested terns fly over their nests during the breeding season today on Fasht al Jarim Island, north of the Bahraini capital Manama

Prime Minister David Cameron recreates the famous Beatles Abbey Road album cover by walking across Abbey Road crossing with Tessa Jowell, former secretary of state for culture, media and sport, on May 20, 2016 in London, England

Jeremy Selwyn/WPA Pool/Getty Images

Prime Minister David Cameron recreates the famous Beatles Abbey Road album cover by walking across Abbey Road crossing with Tessa Jowell, former secretary of state for culture, media and sport in London today

Mayor of London Sadiq Khan (left) meets former mayor of New York Michael Bloomberg at City Hall in London

Stefan Rousseau/PA

Mayor of London Sadiq Khan (left) meets former mayor of New York Michael Bloomberg at City Hall in London today, as the billionaire has warned Brexit would damage Britain’s economy.

A general view of a Neapolitan pizza made to break the world record for the longest pizza ever made, by making a two kilometers margherita

Circo Fusco/EPA

A general view of a Neapolitan pizza made to break the world record for the longest pizza ever made, by making it a two kilometres margherita (16 inch wide) pizza stretching along the city waterfront, in Naples

A police car explodes after being set on fire during an unauthorized counter-demonstration against police violence on May 18, 2016 in Paris

Rielle Sicard/AFP/Getty

A police car explodes after being set on fire during an unauthorized counter-demonstration against police violence today in Paris, as Police across France demonstrate today against the “anti-cop hatred” they say they have endured during a wave of anti-government protests since early March

Photographer Martin Parr looks out from his own caravan which is serving food at the Photo London show in London, Britain, May 18, 2016

Kevin Coombs/Reuters

Photographer Martin Parr looks out from his own caravan which is serving food at the Photo London show in London, Britain today

A bishop takes a photo of Pope Francis during the opening session of the CEI, Italian Episcopal Conference, at the Vatican

Alessandra Tarantino/AP

A bishop takes a photo of Pope Francis during the opening session of the CEI, Italian Episcopal Conference, at the Vatican on Monday

James Massey of Piper's Model Makers cleans the City of London s official 1:500th scale architectural model of central London, which has gone on public display at the City Centre gallery, London.

Dominic Lipinski/PA

James Massey of Piper’s Model Makers cleans the City of London’s official 1:500th scale architectural model of central London, which has gone on public display at the City Centre gallery, London

A Kashmiri man sleeps in a boat along the algae-covered Anchar Lake in Srinagar May 12, 2016

Danish Ismail/Reuters

A Kashmiri man sleeps in a boat along the algae-covered Anchar Lake on Thursday

Former Mayor of London Boris Johnson and fellow Vote Leave campaigner Gisela Stuart MP enjoy an ice cream while in Charlestown, Cornwall, during a Vote Leave campaign visit

Stefan Rousseau/PA

Boris Johnson and fellow Vote Leave campaigner Gisela Stuart MP enjoy an ice cream while in Charlestown, Cornwall, during a Vote Leave campaign visit

A woman walks past chairs displayed on a red carpet in the Palace Festival on the eve of the opening ceremony of the 69th Cannes Film Festival in Cannes, France, May 10, 2016.

Regis Duvignau/Reuters

A woman walks past chairs displayed on a red carpet in the Palace Festival on the eve of the opening ceremony of the 69th Cannes Film Festival in France today

 Emergency forces and shoppers take place in a simulated terror attack at the Trafford Centre on 10 May, 2016 in Manchester, England

Sean Hansford/MEN – Pool / Getty Images

Emergency forces and shoppers take place in a simulated terror attack at the Trafford Centre in Manchester, England today

Media members sit against the panoramic view of Kuala Lumpur from a skybox during a media preview at Kuala Lumpur Tower in Kuala Lumpur, Malaysia, 05 May 2016. Skybox, 421 metres above ground level will be the latest tourists attraction at Kuala Lumpur Tower, the 7th tallest freestanding tower in the world.

Ahmad Yusni/EPA

Media members sit against the panoramic view of Kuala Lumpur from a skybox during a media preview at Kuala Lumpur Tower in Kuala Lumpur, Malaysia, today. Skybox, 421 metres above ground level will be the latest tourists attraction at Kuala Lumpur Tower, the 7th tallest freestanding tower in the world.

Girls perform on the stage of the Mangyongdae Children's Palace in central Pyongyang, North Korea May 5, 2016

Damir Sagolj/Reuters

Girls perform on the stage of the Mangyongdae Children’s Palace in central Pyongyang, North Korea today

Kashmiri Muslims pray as an unseen custodian displays a holy relic, believed to be a hair from the Prophet Muhammad's beard, during celebrations for Miraj-Ul-Alam (ascension to heaven) at Kashmir's main Hazratbal Shrine in Srinagar on May 5, 2016.  Thousands of Muslims converge annually for celebrations at the shrine near the summer capital of the state of Jammu and Kashmir

Tauseef Mustafa/Getty Images

Kashmiri Muslims pray as an unseen custodian displays a holy relic, believed to be a hair from the Prophet Muhammad’s beard, during celebrations for Miraj-Ul-Alam (ascension to heaven) at Kashmir’s main Hazratbal Shrine in Srinagar this morning

Beach-goers stand still as a two-minute siren marking annual Holocaust Remembrance Day in Israel is sounded in Netanya, Israel May 5, 2016

Baz Ratner/Reuters

Beach-goers stand still as a two-minute siren marking annual Holocaust Remembrance Day in Israel is sounded in Netanya, Israel today

American reality-show star Kim Kardashian takes a selfie as she rides on a classic car next to her husband, rap superstar Kayne West in Havana, Cuba, Wednesday, May 4, 2016

Desmond Boylan/AP Photos

American reality-show star Kim Kardashian takes a selfie as she rides on a classic car next to her husband, rap superstar Kanye West in Havana, Cuba. West, Kardashian and members of her reality-show-star family have become the latest celebrities to visit Havana

Young South Korean novice monks play football under lotus lanterns during their training program entitled 'Children Becoming Buddhist Monks' at the Jogye Temple in Seoul on May 4, 2016.

Jung Yeon/AFP/Getty Images

Young South Korean novice monks play football under lotus lanterns during their training program entitled ‘Children Becoming Buddhist Monks’ at the Jogye Temple in Seoul today. A special temple-stay program for children to learn about Buddhism, including shaving their heads and wearing monk’s robes, continues for two weeks ahead of celebrations for Buddha’s birthday on May 14

A Sotheby's  employee  holds Lesedi La Rona Diamond on May Tuesday  3, 2016 in New York City. The diamond the size of a tennis ball that is the largest discovered in more than a century could sell at auction for more than $70 million. Sotheby's says it will offer the Lesedi la Rona diamond in London on June 29

Pascal Perich

A Sotheby’s employee holds the Lesedi La Rona Diamond in New York City. The diamond the size of a tennis ball that is the largest discovered in more than a century could sell at auction for more than $70 million. Sotheby’s says it will offer the Lesedi la Rona diamond in London on June 29