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)

In this Wednesday, August 2, 2017 photo, Borre, an 8-year-old cat sits in a basket next to the canal on the Catboat shelter in Amsterdam, Netherlands. In the heart of the Dutch capital, on a canal near one of the busiest shopping streets, a floating animal sanctuary called The Catboat provides refuge for about 50 stray and abandoned felines. (Photo by Muhammed Muheisen/AP Photo)

National Geographic has created “Air, Land & Sea: the 50 greatest wildlife photographs” exhibition. Here: CT4 Crocodile cave on the Salamat river. Set up with Nathan Williamson last chip rain came while we were with the nomads. (Photo by Michael Nichols/National Geographic)

A collection of whimsical cats in fantastical hats, created by Carol Cavalaris.

The 'Cats that Look like Pin-Up Girls' Tumblr features a variety of similarly posed felines. Once the pinnacle of female sexuality, pin-up girls have changed and evolved throughout the years to become the modern day Playboy Bunnies and Sports Illustrated models they are now recognized as.

An alert-looking Maine Coon during the Grand Prix Royal Canin cat exhibition in Moscow, Russia on December 4, 2016. The breed’s origin is unknown, but one legend claims it is descended from cats brought to the US by an English seafarer called Captain Coon. (Photo by Dmitry Serebryakov/TASS)

Dogs, Pretty, Llilly, and Rocky wait for their turn to be examined by veterinarians during a community campaign for the sterilisation and deworming of dogs and cats in Havana, Cuba February 25, 2016. (Photo by Reuters/Stringer)