A masked reveller parades through the streets on the first day of the carnival season in Lucerne, Switzerland, 12 February 2015. In the background the well known Kappellbruecke bridge. (Photo by Alexandra Wey/EPA)

Dancers perform on their way to attend a rally with former President Luiz Inacio Lula da Silva, “Lula”, supporting President Dilma Rousseff in the historic Lapa neighborhood on April 11, 2016 in Rio de Janeiro, Brazil. Brazil's congressional impeachment committee approved the motion to proceed with President Dilma Rousseff's impeachment process today. A full vote by the lower house of Congress on the impeachment is scheduled for Sunday to decide whether she will face trial. (Photo by Mario Tama/Getty Images)

Festival goer practice yoga during the O.Z.O.R.A. festival on August 4, 2016 in Tolna, Hungary. Ozora is a village in Tolna County. In recent times it has become famous for the O.Z.O.R.A. psychedelic trance festival which has been held on an estate in Ozora near small village Dadpuszta every year since 2004. The first party was called Solipse and took place during the Solar eclipse of August 11, 1999. (Photo by Mohai Balázs/MTI/MTVA)

Vehicles move past a man resting on a taxi, as he waits for passengers, along a road in Karachi, Pakistan, May 5, 2015. (Photo by Akhtar Soomro/Reuters)

Principle Ballet Dancer, Ekaterina Bulgutova, of the Russian State Ballet, with the Nutcracker part of Christmas Ballet Season in Cardiff which starts at St Davids Hall on December 20, 2016 in Cardiff, England. (Photo by Kiran Ridley/Barcroft Images)

Reuters multi-award winning photographers are celebrated here in a three part retrospective on the 30th anniversary of the service's launch. They have captured dramatic images illustrating the human tragedy of natural disaster and war as well as the fallout of economic events across the continents, creating iconic images, recognised around the world. Here: an injured soccer fan is carried to safety by a friend after a wall collapsed during violence between fans before the European Cup final between Juventus and Liverpool at the Heysel stadium in Brussels, May 29, 1985. 39 people died, and a further 600 were injured. (Photo by Nick Didlick/Reuters)

A participant of “Bread Procession of the Saint”, takes part in the ceremony in honor of Domingo de La Calzada Saint (1019-1109) who helped poor people and pilgrimage, in Santo Domingo de La Calzada, northern Spain, Wednesday, May 11, 2016. Every year during spring season, “Las Doncellas” (White Virgins), hold on their head a basket cover with white cloth while they walk past along of this old village in honor of the saint. (Photo by Alvaro Barrientos/AP Photo)

An art installation formed with milk churns, made by land art artist Gerard Benoit a la Guillaume, is seen at the Chenau de Mayen in the resort of Leysin, Switzerland August 7, 2015. More than 80 milk churns were placed between the Tour d'Ai and the Tour de Mayen summits at an altitude of 2,000 meters (6,561 feet) above sea level under the direction of the artist, to be photographed for his ongoing art project entitled “Milk churns without borders”. (Photo by Denis Balibouse/Reuters)