Iceland's Plains of Þingvellir ("The Thing Fields")

History
The Icelandic Alþingi claims to be the longest running parliament in the world.

Foundation
Its establishment, as an outdoor assembly or thing held on the plains of Þingvellir ("Thing Fields") from about the year 930 AD, laid the foundation for an independent national existence in Iceland. To begin with, the Althing was a general assembly of the Icelandic Commonwealth, where the country's most powerful leaders (goðar) met to decide on legislation and dispense justice. All free men could attend the assemblies, which were usually the main social event of the year and drew large crowds of farmers and their families, parties involved in legal disputes, traders, craftsmen, storytellers and travellers. Those attending the assembly lived in temporary camps (búðir) during the session. The centre of the gathering was the Lögberg, or Law Rock, a rocky outcrop on which the Lawspeaker (lögsögumaður) took his seat as the presiding official of the assembly. His responsibilities included reciting aloud the laws in effect at the time. It was his duty to proclaim the procedural law of Althing to those attending the assembly each year.

Lögrétta
Public addresses on matters of importance were delivered at the Law Rock and there the assembly was called to order and dissolved. The Lögrétta, the legislative section of the assembly, was its most powerful institution. It comprised the 39 district Chieftains (goðar) plus nine additional members and the Lawspeaker. As the legislative section of Althing, the Lögrétta took a stand on legal conflicts, adopted new laws and granted exemptions to existing laws. Althing of old also performed a judicial function and heard legal disputes in addition to the spring assemblies held in each district. After the country had been divided into four quarters around 965 AD, a court of 36 judges (fjórðungsdómur) was established for each of them at Althing. Another court (fimmtardómur) was established early in the 11th century. It served as a supreme court of sorts, and assumed the function of hearing cases left unsettled by the other courts. It comprised 48 judges appointed by the goðar of Lögrétta.

The end in 1262
When the Icelanders submitted to the authority of the Norwegian king under the terms of the "Old Covenant" (Gamli sáttmáli) in 1262, the function of Althing changed. The organization of the commonwealth came to an end and the rule of the country by goðar ceased.

Also see

 * 1) Parliament
 * 2) Parliaments and presidential palaces

Sorces
http://www.thingvellir.is/history/the-law-rock.aspx http://www.althingi.is/pdf/enska.pdf https://en.wikipedia.org/wiki/Althing