Complex sentence: "Nail trees" are well known in Southeastern Europe and are found in many cities in Hungary, Romania (in Transylvania) and other countries of the former Austro-Hungarian Empire; the Vienna Stock im Eisen is the oldest preserved nail tree.
Split into simpler sentences: Nail trees are well known in Southeastern Europe and are found in many cities in Hungary, Romania (in Transylvania) and other countries of the former Austro-Hungarian Empire. The Vienna Stock im Eisen is the oldest preserved nail tree.