Þingvellir (Thingvellir), 50 km (31 miles) to the east of Reykjavík, is the national shrine of Iceland. Iceland's most historic site, and one of the country's most beautiful places, it is also part of The Golden Circle tour. The oldest existing parliament in the world first met here in AD930. The Alþing met here every year to enact laws, including the law passed in AD1000 to introduce Christianity into the island. Thingvallavatn is the largest lake in Iceland, 83 km2 and over 100m deep. Þingvellir National Park is now a protected UNESCO national heritage site.