The second in a series of Tower exhibitions focusing on contemporary art and its roots offers a rare look at the black-on-black paintings that Rothko made in 1964 in connection with his work on a chapel for the Menil Collection in Houston. A recording of Morton Feldman's Rothko Chapel (1971), the haunting music originally composed for that space, accompanies the exhibition in the spacious East Building Tower Gallery.  In the Tower: Mark Rothko closes on January 9th at the National Gallery of Art in Washinton.  www.nga.org