This combination of April 15, 2013 and April 2, 2014 photos show a police officer clearing Boylston Street following a bomb blast near the finish line of the 2013 Boston Marathon, and pedestrians crossing at the same corner nearly a year later in Boston. (Photo by Charles Krupa/AP Photo)

A scene showing one of the first trench battles is prepared for the opening of the 3D Panorama exhibition “Memory talks. The road through war” in the former Sevcabel port in St. Petersburg, Russia, 16 September 2019. Various 3D dioramas – containing genuine wartime items such as aircraft, tanks and artillery in original size – allow visitors to walk through scenes from the beginning to the end of WWII without any museum barriers. The exhibition opens from 19 September 2019 to May 2020. (Photo by Anatoly Maltsev/EPA/EFE)

An installation consisting of a series of bird boxes is displayed in a tree in Duncan Terrace Gardens in Islington on March 24, 2011 in London, England. The boxes by artists Bruce Gilchrist and Jo Joelson of “London Fieldworks”, were designed to reflect the architecture of the Georgian terraces and flats that surround the park in the community gardens. (Photo by Dan Kitwood/Getty Images)

An Army Sikorsky VH-34s Choctaw helicopter once used to transport President Dwight D. Eisenhower sits in a field at the 309th Aerospace Maintenance and Regeneration Group boneyard Thursday, May 14, 2015 at Davis-Monthan Air Force Base in Tucson, Ariz. President Eisenhower became the first chief executive to be transported by helicopter. Presidents Eisenhower and John F. Kennedy were transported in VH-34 helicopters and VH-34's served as “Army One” from 1958 through 1963. (Photo by Matt York/AP Photo)

The sanctuary of Lourdes flooded, in Lourdes, southwestern France, Tuesday, June 18, 2013. French rescue services and police are evacuating hundreds of pilgrims from hotels threatened by floodwaters from a rain-swollen river in the Roman Catholic shrine town of Lourdes. (Photo by Bob Edme/AP Photo)

This Monday, September 15, 2014 photo shows glazed bricks displayed at the Iraqi National Museum in Baghdad. The Islamic State militants seek to purge society of all influences that don't conform with their strict, puritanical version of Islam. That means destroying not only relics seen as pagan but also Muslim sites they see as contradicting their ideology, particularly Sunni Muslim shrines they see as idolatrous as well as mosques used by Shiites, a branch of Islam they consider heretical. (Photo by Hadi Mizban/AP Photo)

CHALLOCK, ENGLAND - MARCH 31: Tony Hall walks with his dog through an installation entitled 'Super Kingdom', which hangs in trees in King's Wood as part of the Stour Valley Arts project on March 31, 2011 in Challock, England. The works by artists Bruce Gilchrist and Jo Joelson of 'London Fieldworks' consist of a series of interesting animal habitats, modelled on the palaces of Stalin, Ceauscescu and Mussolini, and offer nesting sites to many native and migrant species. (Photo by Dan Kitwood/Getty Images)

A Nicole Miller designed football is displayed at the unveiling of the CFDA Footballs Wednesday, January 20, 2016, at the NFL headquarters in New York. In celebration of Super Bowl 50 and in support of the NFL Foundation, the NFL and the Council of Fashion Designers of America have collaborated on 50 Bespoke Designer Footballs created by CFDA Members. (Photo by Frank Franklin II/AP Photo)