The ancient city of Rome wasn't built in a day, but now that city, along with all its famous landmarks, can be digitized in just a matter of hours. A new computer program under development at the University of Washington in Seattle combs through hundreds of thousands of tourist photos on Flickr and other photo sharing sites and reconstructs the city – pixel by pixel. Now, viewers can fly around many of Rome's famous landmarks on their computer in far more detail than they'd ever be able to on current virtual map programs such as Google Earth. The new technique may one day create online maps that offer viewers a virtual-reality experience. The software could build cities for video games automatically, instead of doing so by hand.