For centuries, this gate was the busiest trade hub in the city, the primary entry point for essential supplies coming from the French region of Alsace. But as you walk through the arch, look for a peculiar small detail on the facade: a historical letterbox. This box features the Basel Dove, or Basler Dybli, designed by the famous architect Melchior Berri. In 1845, Basel released its first postage stamp featuring this same dove, which was actually the first three-colored stamp in the entire world. It is a small but powerful reminder that this site transitioned from a medieval fortress into a hub of modern communication and commerce. Even as the rest of the city walls were torn down in 1859 to allow the city to grow, the people of Basel fought to keep the Spalentor standing because of its deep cultural significance.