In Omdurman, the largest city in Sudan, the Qadiriyya Sufi order meets every Friday outside Sheikh Hamed Al Nil mosque, which houses the tomb of their 19th century Sufi leader. (Photo by Ala Kheir, John Burns and Ibrahim Algrefwi/Brownbook)

Israeli soldiers fire a 155mm self-propelled howitzer towards the Gaza Strip from their position along the border in the southern Israeli city of Sderot on May 20, 2021. Israel is studying whether conditions are right to stop bombing Palestinian militants in Gaza but is preparing for “more days” of strikes if necessary, an Israeli military source said today. Diplomats stepped up efforts today toward a ceasefire to stem 10 days of deadly violence between Israel and armed Palestinian groups in Gaza as air strikes again hammered targets in the enclave. (Photo by Jack Guez/AFP Photo)

Subway passengers walk past bronze sculptures representing the Soviet people at the Ploshchad Revolyutsii metro station in Moscow, on November 14, 2012. The station was opened in 1938. (Photo by Kirill Kudryavtsev/AFP Photo)

A PSE&G utility worker watches the Navy's Blue Angels and the Air Force's Thunderbirds conduct “a collaborative salute” to honor those battling the COVID-19 pandemic with a flyover of New York and New Jersey, Tuesday, April 28, 2020, in this view from Jersey City, N.J. (Photo by Charles Sykes/Invision/AP Photo)

A dog walks past a mural by street artist Alex Martinez outside a shop which sells bags at Psiri area, central Athens, on Thursday, January 25, 2018. (Photo by Petros Giannakouris/AP Photo)

A seagull files over a man sitting at a coffee shop backdropped by the Bosporus Strait in Istanbul, Tuesday, November 17, 2020. (Photo by Emrah Gurel/AP Photo)

A man prays to mourn victims of the March 11, 2011, earthquake and tsunami in front of a ship brought ashore by the disaster in Kesennuma, Miyagi Prefecture, Japan. (Photo by Kyodo via Reuters)