The Ile de la Cite is one of two natural islands in the Seine within the city of Paris (the other being the Ile Saint-Louis). It is the centre of Paris and the location where the medieval city was refounded. The western end has held a palace since Merovingian times, and its eastern end since the same period has been consecrated to religion, especially after the 10th century construction of a cathedral preceding today's Notre Dame. The land between the two was, until the 1850s, largely residential and commercial, but since has been filled by the city's Prefecture de Police, Palais de Justice, Hotel-Dieu hospital and Tribunal de Commerce. Only the westernmost and northeastern extremities of the island remain residential today, and the latter preserves some vestiges of its 16th century canon's houses.