BERLIN (Reuters) - Police ordered the immediate evacuation of part of southern Berlin and imposed temporary road, rail and metro closures after building workers unearthed a unexploded World War Two bomb on the site of a former railway siding. Bomb disposal experts were due to move into place once the area, a radius of 500 meters around the 250kg bomb in the southern borough of Schoeneberg, had been evacuated, Berlin police said in a tweet.