The CBRE Urban Photographer of the Year competition – now in its ninth year – encourages professional and amateur photographers to capture cities at work. Here: Dog Walker – 15:00. The competition allows photographers to enter up to 24 images, one representing each hour of the day. (Photo by Johanna Siegmann)

Students pose for a pictures taken by their friends during spring break on the beach in the resort city of Cancun, Mexico, February 27, 2009. (Photo by Israel Leal/AP Photo)

Two traditional folk dancers performing in Teheran, Iran. (Photo by Keystone Features/Getty Images). 25th January 1961

Tennis star Maria Sharapova poses with a Porsche 911 RSR race car at the 2016 Los Angeles Auto Show in Los Angeles, California, U.S November 16, 2016. (Photo by Mike Blake/Reuters)

Chinese models with animal-themed body paintings pose during a campaign for animal protection at Sanya Color Zoo in Sanya city, south China's Hainan province, 10 January 2016. The girls wearing strapless bras and short pants only were colored with animal-themed paintings such as zebra, cheetah, tiger and peacock. They paraded throughout the newly-opened Sanya Color Zoo and met visitors to take pictures, causing envies from netizens living in north China who are suffering chills. (Photo by Imaginechina/Splash News)

Children carrying guns and flags or wearing Soviet-style uniforms have become a common sight at Victory Day parades and other events in Russian-controlled Crimea. Russian and Ukrainian human rights activists have warned that such displays point to a growing trend of promoting Russian patriotism among kids on the Crimean peninsula, annexed from Ukraine in 2014. Here: A young Crimean girl wears military-type clothes during a Victory Day celebration in Sevastopol on May 9, 2018. (Photo by Oleksandra Surgan/Radio Free Europe/Radio Liberty)

Winner. “I took this vertical image in the Quarry Bay district of Hong Kong during the dusk ‘blue hour’, when there was a perfect balance between the ambient light in the sky and the artificial lights of the high-rise residential buildings”. (Photo by Jatinder Heer/The Guardian)

There are many types of collections. Some are formed by purposefully collecting certain objects, such as stamps or coins. However, some collections are only a byproduct of an obsession, a quirk of mind. For example, Paul Brockmann got into the habit of buying his girlfriend and later his wife a dress every time they went ballroom dancing. It might seem excessive to some, but it was his way of showing his affection. Overtime, this collection grew to be enormous, counting 55,000 dresses in total. Basic math tells us that either they went ballroom dancing three times per day for every day of their lives, or he bought them in huge bundles every time.