This week's Skywatch Friday features a 70-by-70-foot mural on an air-intake building of the Central Artery tunnel. You can find this mural between Summer and Congress streets, and is the work of Otavio and Gustavo Pandolfo. The Brazilian twin brothers are known as Os Gemeos. The mural is co-sponsored by the Rose Kennedy Greenway and the Institute of Contemporary Art. The mural will be on display through Nov. 25, 2012.