Bici Palermo Tuning – a group of teenagers from the Sicilian capital Palermo – spend anything up to €1,300 customising their bikes with car batteries and multiple speakers to develop thunderous sound systems. The police are not impressed. (Photo by Matteo de Mayda/Cosimo Bizzari/The Guardian)

Željava Air Base, situated on the border between Croatia and Bosnia and Herzegovina under Plješevica Mountain, near the city of Bihać, Bosnia, was the largest underground airport and military air base in the former Yugoslavia, and one of the largest in Europe. (Photo by Thomas Windisch/Exclusivepix Media)

Participants dance during the West Indian Day Parade in the Brooklyn borough of New York September 5, 2016. The Labor Day Carnival (or West Indian Carnival) is an annual celebration held on American Labor Day (the first Monday in September) in Crown Heights, Brooklyn, in New York City. (Photo by Eric Thayer/Reuters)

City stairways grey, cold concrete which is often dirty. These Street Artists around the world decided to do something about it. What they have done is nothing short of phenomenal. You won’t believe it. You’ve have to see these incredible transformations that took these stairs from dull to beautiful!

A man fires his pistol in the air during a celebratory rally after the United Nations approved a no fly zone over the country on March 18, 2011 in Tobruk, Libya. Libya declared an immediate cease-fire after the UN vote but reports indicate that Muammar Gaddafi's forces were still shelling two cities. (Photo by Joe Raedle/Getty Images)

Revelers celebrate the Indian festival of Holi on the deck of the ship Peking at South Street Seaport in Manhattan March 19, 2011 in New York City. The Hindu festival of Holi , also known as the Festival of Colors, marks the arrival of spring where participants throw colored powder and water on one another. Many of the New York participants are Indian-American.

City workers transport a load of sandbags to be used in re-enforcing a levee gate past the Yazoo & Mississippi Valley Railroad Station May 11, 2011 in Vicksburg, Mississippi. The Mississippi river at Vicksburg is expected to crest at a record 58.5 feet. Heavy rains have left the ground saturated, rivers swollen, and have caused widespread flooding in Missouri, Illinois, Kentucky, Tennessee, and Arkansas. (Photo by Scott Olson/Getty Images)

Actress Rosario Dawson (“Men in Black II”, “25th Hour”, “Sin City”, “Death Proof”, “Eagle Eye”, “Alexander”, “Percy Jackson and the Olympians”) walks the runway at the Fashion For Relief at Forville market during the 64th Annual Cannes Film Festival on May 16, 2011 in Cannes, France. (Photo by Ian Gavan/Getty Images)