San Luigi dei Francesi keeps three paintings by Caravaggio on the walls they were made for, which very few places anywhere can say. The church belongs to the French in Rome and is still their national church in the city. Walk to the last chapel on the left and there they are. A French cardinal, Matteo Contarelli, left the money for that chapel and died before it was decorated; the commission eventually reached Caravaggio, not yet thirty and with nothing public to his name.
He put the calling of Matthew on the left wall and his killing on the right, and added the altarpiece between them afterwards. The two side canvases hang high beneath a real window, and the light painted inside them falls in the same direction. The beam that lights Matthew in his dark room looks as if it comes from the chapel window itself. The altarpiece is Caravaggio's second version, because the first one was refused. The chapel holds about twenty people, and a custodian keeps it quiet.