Guests arrive for the opening ceremony of the Moscow Grand Mosque in Moscow on September 23, 2015.

Muslim pilgrims go around the Ka'aba, at the Grand Mosque in the Saudi holy city of Mecca, late on September 21, 2015.

Pre-Roman tomb unearthed in Pompeii, Italy

Birds sit in their cages during a bird-singing contest in Thailand's southern province of Narathiwat on September 20, 2015.

Yemenis inspect the rubble of UNESCO-listed buildings that were destroyed by air strikes carried out by Saudi Arabia in the old city of the Yemeni capital Sana’a, on September 19, 2015.

A 13-year-old Syrian boy plays the violin in front of a police barricade as he marches with other migrants on a highway near Edirne on September 19, 2015.

Picture shows waste in a waterway leading into the Ganges River in India on September 17, 2015. The Ganges is heavily polluted with raw sewage, animal and human corpses, and industrial waste entering the river.

A Yemeni boy stands in the rubble of buildings on September 17, 2015 which were destroyed by air strikes carried out by the Saudi-led coalition in the capital Sana’a.

Indonesia police release turtles into the sea at a beach in Kuta, near Denpasar on the Indonesian resort island of Bali on September 17, 2015.

Hungarian police clash with asylum seekers