Old Heidelberg, Dog with Pipe, 1905. (Photo by Detroit Publishing Company)

Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

An Indian soldier from the international peace keeping force (IPKF) instructs young Sri Lankan recruits in shooting, part of the training given to the citizen's volunteer force in the North-Eastern Sri Lankan city of Batticaloa, September 28, 1989. (Photo by Barbara Walton/AP Photo)

Fossilized whale bones are on display outside the Wati El Hitan Fossils and Climate Change Museum, a UNESCO natural World Heritage site, on the opening day, in the Fayoum oasis, Egypt, Thursday, January 14, 2016. Egypt has cut the ribbon on the Middle East's first fossil museum housing the world's largest intact skeleton of a "walking whale" in an attempt to attract much-needed tourists driven off by recent militant attacks. The construction of the much-hyped Fossils and Climate Change Museum was covered a 2 billion euros (2. 17 billion dollars) grant from Italy, according to Italian Ambassador Maurizio Massari. Its centerpiece is an intact, 37-million-year-old and 20-meter-long skeleton of a legged form of whale that testifies to how modern-day whales evolved from land mammals. The sand-colored, dome-shaped museum is barely discernible in the breathtaking desert landscape that stretches all around. (Photo by Thomas Hartwell/AP Photo)

People watch a total solar eclipse from the Bay Bridge in Palu, Central Sulawesi, Indonesia March 9, 2016 in this photo taken by Antara Foto. The rare astronomical event is being witnessed Wednesday along a narrow path that stretches across 12 provinces encompassing three times zones and about 40 million people. (Photo by Mohamad Hamzah/Reuters/Antara Foto)

People wrapped in blankets sit on the road as they are evacuated from a hotel after an earthquake in Kumamoto, southern Japan, in this photo taken by Kyodo April 14, 2016. A powerful earthquake with a magnitude of 6.5 knocked over buildings in southern Japan on Thursday evening, and police said people may be trapped underneath. (Photo by Reuters/Kyodo News)

A general view showing the shipwrecked cruise ship Costa Concordia in an upright position after the salvage operations in Giglio island, Italy, 17 September 2013. Salvage crews pulled off a major engineering feat when they straightened the listed Costa Concordia cruise ship from the rocks it had been wedged against for the past 20 months. The delicate operation took 19 hours and was completed at 4 am (0200 GMT). The vessel ran aground near the island of Giglio, in Tuscany, in an accident that made world-wide news. (Photo by Angelo Carconi/EPA)

In this two photo combination picture, the Eiffel Tower with its usual lighting at left, and after the lighting was switched off at right, at the occasion of the Earth Hour, in Paris, France, Saturday March 28, 2015. This Saturday, 28 March 8:30 p.m. local time, individuals, businesses, cities and landmarks around the world are switching off their lights for one hour to focus attention on climate change. (Photo by Remy de la Mauviniere/AP Photo)