The OMR gallery , the oldest and best established of the neighborhood galleries , housed in a regal 19th-century building on the corner of Plaza Río de Janeiro ( Plaza Río de Janeiro 54 ; 52-55-5511-1179 ; www.galeriaomr.com ) , adds its own particular slant to contemporary art with a floor that lists sharply to one side , the result of settling soil ( Roma was built on a dry lake bed ) .