During the construction of the École Militaire, the market gardens between the new buildings and the Seine were transformed into a training ground, or Champ-de-Mars. From 1780 onwards, it was opened to the public, who was able to witness the very first hot-air balloon flight attempts here. The Champ-de-Mars has also been the setting for patriotic gatherings, and a fair-ground, when it hosted Universal Exhibitions. Nowadays, this huge garden, part formal, part landscaped, is a popular venue for major events, such as the traditional 14 July firework display.