Collinsville is a city located mainly in Madison County and partially in St. Clair County, Illinois, United States. As of the 2020 census, the city had a population of 24,366. Collinsville is approximately east of St. Louis, Missouri, and is part of that city's Metro East area. Collinsville is the location of Cahokia Mounds State Historic Site, a National Historic Landmark and UNESCO World Heritage Site. This prehistoric urban complex is estimated to have had a population of thousands at its peak, long before European exploration in the area. The city is also known for the Brooks Catsup Bottle Water Tower, the world's largest ketchup bottle, and is billed as the world's horseradish capital. History Cahokia, the largest Pre-Columbian settlement north of Mexico, was developed by the Mississippian culture and is located in what is now the westernmost part of Collinsville. At its peak about 1200 CE, Cahokia had a population of 20,000-30,000, more than any city in the present-day United States until after 1800. It includes Monks Mound, the largest prehistoric earthwork in the Americas, and more than 70 surviving smaller mounds. Monks Mound is larger at its base than the Great Pyramid of Giza. During the French colonial era of its Illinois Country, a group of French Catholic monks had a settlement on Monks Mound, after whom it was later named. They cultivated agriculture on the terraces of the mound. They traded with bands of the historic Illini, who had migrated into the area after the peak of the Mississippian culture. Collinsville was subsequently settled by the Cook family and by a group of German-American settlers who arrived by Conestoga wagon in 1812 from Pennsylvania. They founded Holy Cross Lutheran Church. They also had a hardware store, though they were mainly farmers. Within five or six years, a number of other settlers arrived and began to organize the legal work required to form a town on the site. These original settlers are all buried in the Cook Cemetery or the Old Lutheran Cemetery. Other early settlers are buried in the Old German Cemetery near Sugarloaf Road near Maryville. During World War I, a Collinsville mob, composed mostly of local coal miners, lynched a German immigrant, the only such wartime murder in the country. On April 5, 1918, the mob numbering up to 300 men took Robert Prager from his home and paraded him through the streets barefoot and