Between 2011 and 2018, the Magnus Ladulås project carried out investigations in the founders' graves of Riddarholm Church. The original aim was to further verify the results of investigations carried out in Varnhem Abbey Church in 2002, where three skeletons were attributed to the historical figures Birger Jarl, Duke Erik and Queen Mechtild. Birger Jarl's son Magnus Ladulås is supposed to be buried in Riddarholm Church, and it was generally believed that the location of his grave was found in 1915. It turned out that the conclusions drawn after the 1915-1918 investigations were based on incorrect premises and that the graves did not contain the remains of Magnus Ladulås and his family. Instead, the Magnus Ladulås project shed light on an exciting part of 15th century history. It is clear that the two barrows have a common history and that they must be interpreted as part of a linked sequence of events. The project has shed light on issues such as how the choir was used for burials during the monastic period, which individuals were buried there and the relationship between the royal power and the Grey Friars. The results will now be published in a comprehensive scientific publication in the Stockholm City Museum's report series.