The Knežev Arsenal, or Rector’s Arsenal, was once filled with the industrial sounds of cars and weapons being built. Now, when you enter the empty factory buildings and gritty courtyards, you’re more likely to hear a rock concert or techno music and thousands of cheering fans. Founded in the mid 1800s, the complex, also known as Military Technical Institute, was overseen by a French engineer. At the time, Serbia sought friendly relations with France, and to emulate the country’s economic development. The facilities made the city of Kragujevac a center for weapons…