Fire departments were again formed by property insurance companies beginning in the 17th century after the Great Fire of London in 1666. The first insurance brigades were established the following year. Others began to realize that a lot of money could be made from this practice, and ten more insurance companies set up in London before 1832: The Alliance, Atlas, Globe, Imperial, London, Protector, Royal Exchange, Sun Union and Westminster. Each company had its own fire mark, a durable plaque that would be affixed to the building exterior. A company's fire brigade would not extinguish a burning building if it did not have the correct fire mark.