The prince had been set to begin turning it into a family residence, restoring historic rooms but also putting in elevators and an underground car park, under a government permit. A judge put the work on hold because of "shortcomings" in the architect's plans, saying it was unclear what their full impact would be.
The culture ministry said in a statement that the prince signed an agreement on Friday with the heritage association Historic Paris which "puts an end to the dispute" after weeks of delicate government-supervised negotiations. The Hotel Lambert is considered one of the finest examples of mid-17th-century domestic French architecture, complete with mural paintings by Charles Le Brun and other masters of the day.