Four years ago, the 13th-century castle in Gniew, a town of 7500 people in northeast Poland, was nothing more than some outer walls, a leaking roof and a pile of bricks in the courtyard.

• 格涅是一座小城镇，位于波兰东北部，人口7500人。四年前，这座建于13世纪的古堡外墙破损严重，房顶漏水，庭院里堆积着残砖碎瓦。