The Hôtel de Coislin is one of the epic buildings on the north end of the Place de la Concorde.
On February 6, 1778, the Treaty of Friendship, Commerce and Alliance between the nascent United States and France were signed in the Hôtel de Coislin by Benjamin Franklin, Silas Deane and Arthur Lee for the US side, and by Conrad Alexandre Gérard for France. This made France the first country to recognize the independence of the United States.
It’s a bit hard to find the plaque commemorating the treaty. It can be seen at an angle through the first portal just around the corner on rue Royale. The English text of the plaque reads:
IN THIS BUILDING
ON FEBRUARY 6 TH 1778
CONRAD A. GERARD
IN THE NAME OF LOUIS XVI, KING OF FRANCE,
SILAS DEANE, ARTHUR LEE,
ON BEHALF OF THE UNITED STATES,
SIGNED THE TREATIES
OF FRIENDSHIP, COMMERCE AND ALLIANCE,
BY WHICH FRANCE,
FIRST OF ALL NATIONS,
RECOGNIZED THE INDEPENDENCE
OF THE UNITED STATES.