a wall, in Boston, USA. 一面牆， 波士頓， 美國。

Source: REUTERS

 A wall mural painted by Brazilian graffiti artist Os Gemeos is seen in Boston, USA.(Reuters)
August 8, 2012 « Day in Photos http://blogs.voanews.com/photos/2012/08/08/august-8-2012/
IBTimes Picture This - Daily Photo News http://www.ibtimes.com/articles/373966/20120815/guess-photo-location-world.htm