Blagden Alley between 9th & 10th & M & N Sts NW in Washington, DC
c.1400, from O.Fr. mosaicq "mosaic work," from M.L. musaicum "mosaic work, work of the Muses," neut. of musaicus "of the Muses," from L. Musa (see muse). Medieval mosaics were often dedicated to the Muses.