of Kalisz. The Old Częstochowa became the seat of a county (see Districts of Prussia). During the Napoleonic Wars, in 1807 Częstochowa became part of the Duchy of Warsaw. In 1815 it came under Russian-controlled Congress Poland, in which it remained until World War I. Old Częstochowa remained the seat of a county in 1807–1830. In 1809, the monastery was unsuccessfully besieged by Austrians (see Polish–Austrian War). On April 2, 1813, Jasna Góra was seized by the Russians (see War of the Sixth Coalition), after a two-week siege, and the fortifications were razed that year. In 1821, the government of Congress Poland carried out a census, according to which the population of New Częstochowa was 1,036, while the population of Old Częstochowa was 2,758. Furthermore, almost four hundred people lived in several settlements in the area (Zawodzie, Stradom, Kucelin). The idea of a merger of both towns was first brought up in 1815. In 1819, military architect Jan Bernhard planned and started the construction of Aleja Najświętszej Panny Marii—the Holy Virgin Mary Avenue, which is the main arterial road of the modern city. It connected Old Częstochowa with New Częstochowa. Finally, the two towns were officially merged on August 19, 1826. The new city quickly emerged as the fourth-largest urban centre of Congress Poland; surpassed only by the cities of Warsaw, Lublin, and Kalisz. On September 8, 1862, a patriotic rally took place in the city, in front of St. Sigismund church. As a reprisal, Russian military authorities destroyed app. 65% of Częstochowa's Old Town, and introduced martial law . During the January Uprising, several skirmishes took place in the area of Częstochowa, with the last one taking place on July 4, 1864, near Chorzenice. In 1846 the Warsaw-Vienna Railway line was opened, linking the city with the rest of Europe. After 1870 iron ore started to be developed in the area, which gave a boost to the local industry. Among the most notable investments of the epoch was the Huta Częstochowa steel mill built by Bernard Hantke, as well as several textile mills and paper factories. In 1900, the traveling cinema of brothers Władysław and Antoni Krzemiński came to the city for the first time, after it was founded in Łódź in 1899 as the oldest Polish cinema. In 1909, they settled in Częstochowa and founded Kino Odeon, the first permanent cinema in the city. Up to the Second