Thousands of Dutch citizens studying high-resolution maps at home have located 1200 more possible bronze age burial mounds, almost 38 square kilometers of prehistoric agricultural fields and 900 potential charcoal production sites in two nature reserves. The citizen science project, run by the University of Leiden and local cultural heritage groups, started in April 2020. In total, 6,500 volunteers scanned thousands of maps. Fieldwork was then carried out at 300 potential grave sites and 80 were found to be the real thing. Potentially there are 949 new burial mounds, double how many are currently known, says Leiden archeologist Eva Kaptijn.