An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

As national soccer teams and the photographers who have been covering them start to trickle home from the Brazil World Cup, it’s time to revisit the “On the Sidelines” project. This Reuters Pictures project was billed as a chance for photographers to share “their own quirky and creative view of the World Cup”. Photo: People watch from outside as a dancer performs inside a bar in Porto Alegre June 21, 2014. In a project called “On The Sidelines” Reuters photographers share pictures showing their own quirky and creative view of the 2014 World Cup in Brazil. (Photo by Marko Djurica/Reuters)

Sushi Cats (originally branded as Neko-Sushi) is a series of photographs created by the Japan-based company Tange & Nakimushi Peanuts. In this series the creators have dressed up a number of cats and placed them on top of oversized balls of sushi rice. The kitties don’t look too happy with what is going on, though they do look adorable in their little outfits. Tange & Nakimushi Peanuts didn’t think that making a set of photos was enough, so they’ve also created an Android and iPhone apps featuring Sushi Cats. Moreover, people living in Japan can visit their website, if they wish to order photo prints, postcards, and other items. (Photo by Tange & Nakimushi Peanuts)

From house breaking in Johannesburg to hippos on the loose in Tbilisi to rioters attacking a policewoman in Burundi, Reuters photographers tell the story behind some of the most iconic pictures of the year. Here: Protesters drag a female police officer accused of shooting a protester in the Buterere neighbourhood of Bujumbura, Burundi, May 12, 2015. Goran Tomasevic: Protesters started throwing stones at a group of police, who then started to run away. The policewoman in the photo, Medikintos Inabeza, 33, got left behind and then some protesters started to push her, saying that she had shot a female protestor in the stomach with an AK47 rifle. I didn't see anything of that. There were 5 or 10 protesters pushing the policewoman at first, then others came and joined in. Up to 20 or 30 protesters were surrounding her at one point. The protesters kicked and beat her very badly; I also saw a couple of knives. I thought they were going to kill her... (Photo by Goran Tomasevic/Reuters)

“The Spanish Civil War (The Crusade among Nationalists, Fourth Carlist War among Carlists, The Rebellion or Uprising among Republicans) was a major conflict fought in Spain from 17 July 1936 to 1 April 1939. An estimated total of 500,000 people lost their lives as a consequence of the War”. – Wikipedia. Photo: Actors take part in a re-enactment of the “Battle of Areces” that took place during the Spanish Civil War, in Grullos, north of Spain, September 14, 2013. The re-enactment of the historic 1937 battle was organised by the Frente del Nalon Association. (Photo by Eloy Alonso/Reuters)

Soma-Nomaoi is a festival that recreates a battle scene from more than 1,000 years ago. It is annually held for 4 days from July 22 to 25 in Haramachi City, Fukushima Prefecture, in the eastern part of Japan. In this historical event, 600 mounted samurai in traditional Japanese armor, with long swords at their side and ancestral flagstaffs streaming from their backs, ride across open fields. Soma-Nomaoi has been designated an Important Intangible Folk Cultural Property.

Photo: A young woman (C) clad in samurai costume leads other local poeple as she rides her horse during a parade at the annual Soma Nomaoi festival in Minamisoma, Fukushima Prefecture, on July 28, 2012. The traditional full-scale festival kicked off for the first time after the accident of the Fukushima Dai-ichi Nuclear Power Plant following the massive earthquake and the tsunami on March 11, 2011. (Photo by Toru Yamanaka/AFP Photo)

The expertly colourised shots were brought to life by French bank technician, Frédéric Duriez (51). The images were provided by the Valois collection which belongs to the BDIC. “By colourising these photos, I reduce the time that separates us today from this conflict”, said Frédéric. Here: Car cannon sections in firing position, Auxi-le-Château. (Photo by Frédéric Duriez/BDIC/Mediadrumworld.com)

“NASA's Mars rover Opportunity just celebrated its ninth anniversary on Mars – a mission that was originally meant to last just 90 days...” – The Atlantic. Photo: NASA's rover Opportunity visits Victoria Crater, viewed from orbit by the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter in october of 2006. Opportunity is a small dot on the crater's lip, at top right. Opportunity first reached the crater's rim on September 27, 2006. (Photo by NASA/JPL-Caltech/University of Arizona via The Atlantic)