1920-1945 Matthías Þórðarson
In the period 1920-1945 Matthías Þórðarson, general director of the National Museum of Iceland, undertook an extensive study of Þingvellir. He wrote a number of papers and published a book on his findings, together with a map of the parliamentary site and booths.
In an excavation which took place in 1920, he excavated Þorleifshaugur (Þorleifur's Barrow) in connection with an extensive study of the assembly site. According to oral tradition, it was the burial place of Þorleifur jarlaskáld (Þorleifur Poet of Earls), who was slain at Þingvellir and buried "north of the Law Council".
Matthías Þórðarson concluded that the contents of the barrow had been disturbed - hence it had been dug up before. The barrow appeared to be a manmade structure of considerable age. It contained a large amount of rock. He found slight traces of ash and charcoal.