According to the official website: Þingvellir was declared a national park in 1930. A law was passed designating Þingvellir as “a protected national shrine for all Icelanders, the perpetual property of the Icelandic nation under the preservation of parliament, never to be sold or mortgaged.”
Þingvellir is part of a volcanic and fissure region created by the continental drift of the Eurasian and North American plate.