Tallinn Old Town is one of the best-preserved Hanseatic towns in Europe and a UNESCO World Heritage Site since 1997. Cobblestone streets, medieval defense towers, merchant houses and churches dating from the 13th to 15th centuries create a remarkably intact medieval cityscape. It is divided into upper Toompea hill with its parliament and cathedrals, and the lower town that was the commercial heart. The city wall stretches about two kilometers with 20 defense towers, many still open to visitors. It is considered one of the most complete and authentic medieval town centers in Europe