If you’ve ever contemplated the long desert drive to Marfa, Texas to see the work of American sculptor Dan Flavin, a metro trip to the end of the green line won’t seem like too much of an effort. The suburban Santa Maria Annunciata in Chiesa Rossa , an airy 1930s church, contains his last work, designed shortly before his death in 1996. The arrangement of red, yellow and blue fluorescent lights across the altar, apse and transept is a subtle work - the life and clutter of an everyday church goes on beneath it - but its mix of the formal and the emotional is all the more powerful for its setting.