 The "Masjid al-Haram" is the largest mosque in the world and the most expensive single building in the entire world, valued at 100 billion US dollars, as of 2020.It is the site of two of the most important rites of both the Hajj and of the Umrah, the circumambulation around the Ka'bah ("tawaf") and the walking between the two mounts of Safa and Marwa ("sa'ee").The masjid is also the site of the Zamzam Well.