An actor plays an injured passer-by during Exercise Strong Tower, the scene of a mock terror attack at a disused underground station in central London, Britain June 30, 2015. London police held their biggest-ever terrorism drill on Tuesday, pitting the emergency services against a group of marauding attackers, nearly 10 years since four young British Islamists killed 52 people in suicide bombings on London's transport network in July 2005. (Photo by Peter Nicholls/Reuters)

“Hi! I'm Joel, I live in a valley in British Columbia's Rocky Mountains, as close to the forest as I could possibly be! I love to run, bike, jump, eat and create and I hope that you enjoy my work as much as I enjoy creating it!” – Joel Robison. (Photo by: Joel Robison; Source: Flickr)

“Hi! I'm Joel, I live in a valley in British Columbia's Rocky Mountains, as close to the forest as I could possibly be! I love to run, bike, jump, eat and create and I hope that you enjoy my work as much as I enjoy creating it!” – Joel Robison.

Photo: “Under Peaceful Skies”, 2011. (Photo by: Joel Robison; Source: Flickr)

Indian ivory furniture legs in the shape of a goddess from the first century AD are displayed in the 'Afghanistan Crossroads of the Ancient World' exhibition at The British Museum on March 1, 2011 in London, England. Displaying treasures that were in great danger during the years of civil war and Taliban rule, these surviving artifacts reveal Afghanistan's ancient culture, its fragility and its remarkable place in world history. The exhibition opens to the public on March 3 and runs until July 3, 2011. (Photo by Peter Macdiarmid/Getty Images). LONDON, ENGLAND – MARCH 01

General view of the screens in Hyde Park to showing the Royal Wedding on April 29, 2011 in London, England. The marriage of Prince William, the second in line to the British throne, to Catherine Middleton is being held in London today. The Archbishop of Canterbury conducted the service which was attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding and street parties are being held throughout the UK. (Photo by Tom Dulat/Getty Images)

British artist, Mark Coreth sits on top of the “Sydney Ice Bear” carved from a 10 tonne block of ice to illustrate how humans affect climate change in the Arctic at Customs House on June 3, 2011 in Sydney, Australia. The public will be welcomed to touch the bear, and leave an imprint which will begin the melting process and act as a metaphor for how humans affect the environment. The ice bear's has visited six cities on it's global tour since 2009; the visit to Sydney coincides with World Environment Day on June 5. (Photo by Lisa Maree Williams/Getty Images)

“Anish Kapoor CBE RA (born 12 March 1954) is a British sculptor of Indian birth. Born in Mumbai (Bombay), Kapoor has lived and worked in London since the early 1970s when he moved to study art, first at the Hornsey College of Art and later at the Chelsea School of Art and Design”. – Wikipedia

Photo: Workmen install a large-scale sculputure by Anish Kapoor at the Lisson Gallery on October 10, 2006 in London, England. (Photo by Gareth Cattermole/Getty Images)

Jane Howorth from national charity the British Hen Welfare Trust holds Liberty the last ex-battery hen to be rehomed on December 29, 2011 in Chulmleigh, England. The rehoming of Liberty signifies the end of the small battery hen cage, which has been phased out and replaced by enriched cages in preparation of the European Union directive banning the smaller cages from January 1, 2012. (Photo by Matt Cardy/Getty Images)