When Gabriel built the Ecole Militaire (military academy), he made a parade ground or Champ-de-Mars out of the vegetable gardens to be found between the new buildings and the banks of the River Seine. The Champ-de-Mars was the scene of many national festivals under the Revolution, (Fête de la Fédération, Fête de l'Etre suprême). During the 19th century, it was the site of several World Fairs. The present day garden, the work of J. -C. Formigé, dates back to 1923. Nowadays, it is the backdrop for concerts where huge crowds gather around giant screens. Some of the most outstanding examples include the concert conducted by Seiji Ozawa in May 2000, or when Johnny Hallyday performed in June 2000, before an audience of nearly 800,000 people. The Wall for Peace, a transparent structure thought up by Clara Halter and freely inspired by the Wailing Wall in Jerusalem, has been temporarily erected at the bottom of the Champ-de-Mars. Executed by the architect Jean-Michel Wilmotte, the Wall for Peace will shortly be moved to its final home in front of the Unesco headquarters in the Place de Fontenoy.