A masked participant carries a burning matress during the ancient carnival of Zubieta, in the northern Spanish Navarra province on January 30, 2018. The yearly three day festivities, revolving mainly around agriculture and principally sheep hearding, run on the last Sunday, Monday and Tuesday of January where Navarra Valley locals from two villages dress up and participate in a variety of activites as they perform a pilgrimage through each village. (Photo by Ander Gillenea/AFP Photo)

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)

An employee controls the arms of a manned biped walking robot “METHOD-2” during a demonstration in Gunpo, South Korea, December 27, 2016. It stands 13-feet (3,96 m) tall, weighs 1.3 tons and wields a pair of 286-pound (129,73 kg), motion-tracking metal arms. (Photo by Kim Hong-Ji/Reuters)

When Dutch photographer Marcel Heijnen moved to Hong Kong, the territory’s shop cats instantly caught his eye. While the “feline emperors” are the stars, his shots also offer insights into Hong Kong’s wares, from dried fish to paper. Here: Hong Kong Shop Cats #17. (Photo by Marcel Heijnen/Blue Lotus)

A person walks their dog in the morning mist at sunrise in Greenwich Park in south London on November 9, 2020. (Photo by Daniel Leal-Olivas/AFP Photo)

A model poses with a motorcycle and a car on a racing track at the Essen Motor Show in Essen, Germany, November 27, 2015. (Photo by Ina Fassbender/Reuters)

These stunning coloured images show detailed x-ray images of everything from skulls to light bulbs. Artist Paula Fontaine, from Westminster Massachusetts, created the images using a process called digital map painting. To create the images the x-ray emission source – the head of the machine on an arm which focuses the beam – is placed over the object. Paula then retreats behind a shielded screen before activating the x-ray exposure. Here: Brain storm, conceptual composite X-ray. (Photo by Paula Fontaine/Barcroft Media)

The giant inflatable Rubber Duck installation by Dutch artist Florentijn Hofman floats on the Parramatta River, as part of the 2014 Sydney Festival, in Western Sydney, January 10, 2014. The creation is five stories tall and five stories wide and has been seen floating in various cities around the world since 2007. (Photo by Jason Reed/Reuters)