Scientists from the University of Washington have used advanced photo analysis and modelling techniques to generate fly-though representations of the Colosseum, the Trevi fountain and the Croatian city of Dubrovnik.
The models are created entirely from data taken from images uploaded by members of the public on to the photo-sharing website.
The team used a specially-devised algorithm to detect and arrange photos showing various angles of the same building. The same algorithm then analysed these images - taking into account the viewpoint of the photographer - to produce composite 3D models.
Rome's most famous landmarks were generated in less than 24 hours from 150,000 photos, while 250,000 images were scanned to make 3D models of Venice.
The method is basically an enhanced verison of Microsoft's Photosynth application, with processing improvements allowing modellers to turn their intentions to entire cities - starting with the historic centre of Dubrovnik.
Although the Croatian city was recreated from just 4,600 images, the researchers says that the complex modelling techniques could be used to map huge areas in detail.
"We can now process truly huge data sets - the big breakthrough here was being able to match the images fast," Sameer Agarwa, assistant professor at the University of Washington's Graphics and Imaging Laboratory told Popular Science.
The researchers say that they now plan to work on using still images to create photo-realistic 3D tours, rather than just sketchy models.
They hope to preserve threatened urban areas - like the sinking island-city of Venice - for future generations, and say that the technology could also be used to create hyper-realistic video games and GPS systems.
In the selection of videos posted on YouTube, the scattered 3D pyramids indicate the location of the photographers who took the original images.