A combination photo shows some of the colourful doors seen in Rabat's Medina and Kasbah of the Udayas, September 2014. UNESCO made Rabat a World Heritage Site two years ago and media and tour operators call it a “must-see destination”. But it seems the tourist hordes have yet to find out. While visitors are getting squeezed through the better-known sites of Marrakesh and Fez, the old part of Rabat - with its beautiful Medina and Kasbah of the Udayas - remains an almost unspoiled oasis of calm. Smaller and more compact, its labyrinths of streets, passages and dead ends are a treasure trove of shapes and colours, of moments begging to be caught by the photographer's lens. (Photo by Damir Sagolj/Reuters)

Waldo, a 6-year-old Tibetan Terrier belonging to Susan and Mike Leverette of Sebastian, competes in the third heat of the medium dogs division at the Hang 20 Surf Dog Classic at Carlin Park in Jupiter Saturday, August 29, 2015. “The waves are a little bigger than we are used to”, said Susan. (Photo by Bruce R. Bennett/The Palm Beach Post)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

The truth can never be seen right away. Only by looking from a certain angle can we view the true nature of things. At other times, only with the help of some special object can we discern order in chaos. Anamorphosis is a form of art that allows us to see an object only by viewing it from a certain angle or by using cylindrical or conical mirror. Unsurprisingly, the first person in history to ever use this type of technique was the Leonardo Da Vinci. During late Renaissance period this technique was popularized as a children’s toy. Now, however, few people use this form of imagery due to its intricacy. Istvan Orosz, born in 1951, is one of the few people who specialize in anamorphosis. In our opinion, his most stunning piece of art is the one where a shipwreck scene turns into a portrait when viewed through a cylindrical mirror. (Photo by Jonty Hurwitz)

“The Independence day”. While on storm chasing expeditions in the Tornado Alley in USA I have encountered many photogenic supercell storms. This photograph was taken while we were approaching the storm near Julesburg, Colorado on My 28th, 2013. The storm was tornado warned for more than one hour, but stayed an LP storm through all its cycles and never produced a tornado, just occasional brief funnels, large hail and some rain. Photo location: Julesburg, Colorado, USA. (Photo and caption by Marko Korošec/National Geographic Photo Contest)

“Microscope images forge an extraordinary bond between science and art, said Hidenao Tsuchiya, Olympus America's Vice President and General Manager for the Scientific Equipment Group. We founded this competition to focus on the fascinating stories coming out of today's life science research laboratories. The thousands of images that people have shared with the competition over the years reflect some of the most exciting work going on in research today – work that can help shed light on the living universe and ultimately save lives. We look at BioScapes and these beautiful images as sources of education and inspiration to us and the world”. – OlympusBioScapes

Photo: Pretarsus of the third leg of a female drone fly (Eristalis tenax), ventral view, by Dr. Jan Michels, Institute of Zoology, Christian-Albrechts-University of Kiel, Germany. (Photo by Olympus BioScapes)

“The Reward”. “A spot that a friend and I found that takes a bit of effort to get to. Needs the right swell and wind direction to come together for the backwash to really happen. We had been many times with OK results, but this morning everything lined up perfectly and I was rewarded with this split-second moment in time under some amazing morning light”. (Photo by Scott Harrison/2019 UK Surf Photo of the Year)