The Louvre and the Tuileries garden form, at the heart of the 1st arrondissement of Paris, a continuous heritage ensemble linking the world's most visited museum to the Place de la Concorde. A former medieval fortress turned royal palace, the Louvre has housed the national museum's collections since 1793, entered since 1989 through the glass pyramid designed by I. M. Pei. To the west, the Tuileries garden, laid out in 1564 for Catherine de' Medici and redesigned by André Le Nôtre in 1664, covers roughly 25 hectares. Between the two, the Carrousel garden, crossed by the Arc de Triomphe du Carrousel, has displayed around twenty sculptures by Aristide Maillol since 1964.