The Ferme Générale (General Farm) was a much-hated private tax-collecting organization that built a wall encircling Paris as a means to collect tolls on goods entering the city*
* As opposed to those much-loved private tax-collecting organisations. Those guys are a bloody riot!
The wall was marked by 62 barrier-gates built in classical style, many of which still stand today. Suppression of the Ferme Générale was one of the most popular acts of the National Assembly.