What happened.....?

Question

Looking at a 1950's series twenty dollar bill and a 2004 series twenty both say the white house under the building on the back, but it is two different buildings and surrounding anyone know?

Answer 1

It was an anti-counterfeiting measure. According to wikipedia, in 1998 the $20 bill "[r]eceived a completely new appearance to further deter counterfeiting; the picture of the White House was changed to the north side view [from the south side view]."

There were other changes made: "A larger, off-center portrait of Jackson was used on front, and several anti-counterfeiting features were added, including color-shifting ink, microprinting, and a watermark. The plastic strip now reads "USA 20" and glows green under a black light."