World Cup stadium built on bird sanctuary

The Kaliningrad Stadium, more than 750 miles from Moscow, will host four matches in the 2018 FIFA World Cup. But the Associated Press reports the stadium was built on top of one of the last remaining bird sanctuaries in the region. Construction included pouring over one million tons of sand onto a wetland that filtered polluted water from the nearby Pregolya River. These images show the site from July 2011 to June 3, 2018. The depicted islands and their bridges happen also to have been subject of a notorious mathematical problem, from when Kaliningrad was the Prussian city of Königsberg. The Seven Bridges of Königsberg were untangled by Leonhard Euler in year 1736.