my Chronicles from the Sprawl (18/n) - Lost in Translation

I saw this billboard in the L'Enfant Plaza metro station, in Washington. A few dictionaries and encyclopedias latter I haven't figure out yet the meaning of the word "score" in this context.

Satellite Photo:

http://maps.google.com/maps?f=q&hl=en&q=38.88390,-77.024964&ie=UTF8&om=0&t=k&z=17&ll=38.883901,-77.024964&spn=0.004126,0.013475



(

a photo of the Lincoln Memorial - and link to the Satellite Photo - is here:

http://lasers-in-the-jungle.blogspot.com/2006/09/my-chronicles-from-sprawl-15n.html

)

UPDATE:

"A group of twenty units is often referred to as a score"

cf. http://en.wikipedia.org/wiki/20_(number)