Google Street View
The US Debt Clock is a large bill-board size digital clock which shows the current gross national debt of USA as well as each American family's share of the debt. The digital display is continuously updated automatically.
The clock is installed on the side wall (facing W 44th street) of Durst building at 1133 Avenue of the Americas, New York.
When the clock was installed at this location in 2004 its designer's hadn't thought that US National debt will ever (or soon) reach the ten trillion (10,000,000,000) dollar. With mounting debt, the clock ran out of digits on September 30, 2008 when the US debt passed the 10 trillion dollar mark. In order to accommodate one additional digit, the extreme left LED module, which showed the $ sign, was converted into figure of '1' and the clock is now capable of showing the debt value above ten trillion.
Incidentally the American debt has crossed the 15 trillion mark on Nov. 16, 2011 afternoon. (Source). (Real-time On-line Debt Clock)
More info: Wikipedia
Credits: I am thankful to Krenek, member Google Earth Community for informing me about US National debt crossing 15 trillion mark.