Farm Arnarbaeli is really a part of a farm hamlet named The Arnarbaeli Hamlet. The farmland is vast, fertile and somewhat boggy. The farmers were among the first to solve that problem by draining the area with ditches. They grazed young bulls in the open spaces of the Hellisheidi moorlands, where the main travel and transport route connected the Southwestern Lowlands and the Capital Area. Those bulls were sometimes too playful and dangerous for the liking of the travellers.
Farm Arnarbaeli was a church site until 1909 and a parsonage for a long time. Its and the Reykir benefices were united and all their parishioners sought services at the Kotstrond Church until a new church had been built and consecrated in the town Hveragerdi.
According the 18th century annals, earthquakes caused collapses of farms and fatal casualties on the 20th of April 1706. The Reverend, Hannes Erlingsson, barely escaped through a gap in a collapsed wall with a baby in his arms. Almost simultaneously an open fishing boat he owned went down with a crew of eleven, all married tenants on his property. On the 6th of September 1896 the farmhouses collapsed again during an earthquake period.
A large ruin on the mound Thingholt within the boundaries of the Arnarbaeli property was declared inviolate.