The Somerville Arts Council yearly Illuminations Tour (http://www.somervilleartscouncil.org/programs/illuminations/index.html) is the annual trolley tour of holiday light displays. The 45-minute tour celebrates the folk-artistry of the many city residents who transform their houses and yards with lights, illuminated ornaments, and shrines of devotion and fantasy during the darkest time of the year.
Tickets for Saturday December 20th 8:45 & 9:15 are available at Blue Cloud Gallery (http://bluecloudgallery.com/) @ 713 Broadway Ball Square Somerville.
