Luxembourg Palace, large Renaissance palace in Paris, on the left bank of the Seine near the Sorbonne. It was built (1615–20) for Marie de' Medici by Salomon de Brosse on the site of a former palace belonging to the duke of Piney-Luxembourg (hence its name), and it was enlarged in the 19th cent. Poussin, Philippe de Champaigne, and Rubens were commissioned to decorate the interior; the 24 panels painted by Rubens are now at the Louvre. The palace was used for the Paris Peace Conference of 1946. It contains valuable paintings, notably those by Delacroix. The beautiful Luxembourg Gardens are also noteworthy.