The name given in tie-in novels to the Paris building that houses the office of the Federation President, seen on screen in Star Trek VI and Deep Space Nine.
The Palais de la Concorde is the building in Paris from which the President of the United Federation of Planets governs. The name is not spoken on screen. It was introduced in the novels, most prominently Keith R.A. DeCandido's Articles of the Federation, which place the tower on the Place de la Concorde.
The office itself does appear in canon. In Star Trek VI: The Undiscovered Country, the Federation President receives the Klingon, Romulan and Starfleet delegations in a room overlooking the Eiffel Tower during the crisis over Chancellor Gorkon's assassination.
The same setting returns in the Deep Space Nine episodes Homefront and Paradise Lost, in which President Jaresh-Inyo meets Sisko and Admiral Leyton there as fear of changeling infiltrators grips Earth.