The Alþingi (parliament (Icelandic) and anglicised as Althingi or Althing) is the national parliament of Iceland. It is the oldest surviving parliament in the world. The Althing was founded in 930 at Þingvellir ("thing fields" or "assembly fields"), situated approximately 45 kilometres (28 mi) east of what later became the country's capital, Reykjavík. Even after Iceland's union with Norway in 1262, the Althing still held its sessions at Þingvellir until 1800, when it was discontinued. It was restored in 1844 and moved to Reykjavík, where it has resided ever since. The present parliament building, the Alþingishús, was built in 1881, made of hewn Icelandic stone. The unicameral parliament has 63 members, and is elected every four years based on party-list proportional representation.
The constitution of Iceland provides for six electoral constituencies with the possibility of an increase to seven. The constituency boundaries and the number of seats allocated to each constituency are fixed by legislation. No constituency can be represented by fewer than six seats. Furthermore, each party with more than 5% of the national vote is allocated seats based on its proportion of the national vote in order that the number of members in parliament for each political party should be more or less proportional to its overall electoral support. If the number of voters represented by each member of the Althing in one constituency would be less than half of the comparable ratio in another constituency, the Icelandic National Electoral Commission is tasked with altering the allocation of seats to reduce that difference.
The current speaker of the Althing is Steingrímur J. Sigfússon.
The Althing claims to be the longest running parliament in the world. Its establishment, as an outdoor assembly or thing held on the plains of Þingvellir ("Thing Fields" or "Assembly Fields") from about 930, 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 the Althing to those attending the assembly each year.
The Gulathing Law was adopted in 930 at the first Althing, introduced by Úlfljótr who had spent three years in Norway studying their laws. The Icelandic laws conferred a privileged status on the Danes, Swedes and Norwegians.
According to Njáls saga the Althing in 1000 declared Christianity as the official religion. By the summer of 1000 the leaders of Iceland had agreed that prosecuting relatives for blaspheming the old gods was obligatory. Iceland was in the midst of unrest from the spread of Christianity that was introduced by travelers and missionaries sent by the Norwegian king Olaf Tryggvason. The outbreak of warfare in Denmark and Norway prompted Thorgeir Ljosvetningagodi, a pagan and chieftan of the Althing, to propose "one law and one religion" to rule over the whole of Iceland, making baptism and conversion to Christianity required by law.