The management of the episcopal mills was usually given to tenants, among whom there were not rarely women. In the 15th century the mills were running 10 mill wheels, a reference to a remarkable business volume.
The preservation of the mills of St. Andrew, named after the nearby cathedral, was up to the bishops of Concordia, too. Two of them wanted to leave their mark on stone, probably in order to document all of the work done by them, but now this stone no longer exist.
After more than 700 years of service the mills were shut down. In 1970 they were acquired by the municipality of Portogruaro. At the beginning of the eighties the dilapidated mills were saved by the courageous intervention of the Minister of Cultural Heritage. So again, the city's contemporary art gallery Ai Molini, that was already resident here in the postwar years, could reopen its doors.