The Farmers-General Wall, a 24-kilometer fortification surrounding Paris, was constructed between 1784 and 1790 to collect the octroi, a tax on goods entering the city. The idea of building such a wall was first proposed to King Louis XVI in 1782 by the Farmers-General, a group responsible for collecting royal taxes. The wall stood about 3.24 meters high and was made of stone, with sections removed to allow the Seine River to flow, to place barriers, or to follow the path of Monceau Park. A 11.60-meter wide path ran along the inner side, while a 30-meter wide boulevard was on the outer side. The wall's route still roughly aligns with the current paths of the city's 2 and 6 subway lines, stretching from the Nation to Étoile stations, passing through Pigalle. The 43 octroi pavilions designed by architect Claude-Nicolas Ledoux were built in a neoclassical style, drawing inspiration from ancient Greek architecture. He called these structures "propylaeum," a term referring to the monumental gateways of Greek temples. However, the pavilions faced criticism as early as 1787, particularly for their high cost. The general controller of finances, Loménie de Brienne, halted construction in 1787 due to the kingdom's severe financial crisis. The writer Louis-Sébastien Mercier criticized these tax offices, which had become grand, columned buildings rather than practical structures. On the night of July 12 to 13, 1789—just two days before the storming of the Bastille—Parisians attacked the wall, setting fire to several barriers, including the one at Passy. They also created numerous breaches in the structure. While accounts vary on how many barriers were destroyed, no definitive number can be confirmed. The pavilions had already drawn criticism, and the wall, intended to fill the king’s coffers, became one of the early targets of the French Revolution. Ledoux was removed from the project in 1789, likely due to the political turmoil. The octroi tax was abolished on May 1, 1791, but it was later reinstated in 1798 by the Directory to fund the city's expenses and support hospices. Although the tax was gone, the wall remained and continued to serve as an administrative boundary. In 1790, the Revolution officially defined Paris's boundaries along the wall, a boundary that lasted until January 1, 1860, when Paris expanded to the Thiers enclosure. The wall was eventually demolished in January 1860, and the city absorbed the surrounding communes in one sweeping move. Today, only four of the original pavilions remain: the rotunda in Monceau Park, the rotunda at la Villette, the barrier of the Throne, and the barrier of Hell. The Monceau Park rotunda is located in one of western Paris’s most elegant parks, while the la Villette rotunda is near the basin of la Villette. The barrier of Hell, now known as Place Denfert-Rochereau, serves as the entrance to the Catacombs, a famous underground ossuary.