Picture this: Mobile phones with cameras serving as the public eye.
Visualize free and abundant bandwidth and storage, allowing most camera phones to be constantly turned on, recording whatever surrounds them. Uploading it to a large scale distributed database of images. This database constantly churns the flow of images, matching their features, averaging out the momentary (people, cars) and retaining the permanent (structures). You can explore any place in the world where someone has carried a cell phone, and get a sense of the place.
These cell phones can also record audio, which can be processed to produce the basic “sound” of a place. By using judicious criteria to filter out some unique sounds and retain some more common ones, this “sound” can be more than white noise. Different sound signatures can also be achieved for different times of the day, different seasons of the year. So you can log in, and visit a mountain river, and see how it looked last winter, frozen under a quiet blanket of snow. Then look at it this spring, rushing and rumbling.
You’ll definitely be able to see the tower of Pisa in great detail, inside and out, at all times of the year. There will be no lack of pictures and sounds for that one. The soundtrack will probably retain a lot of crying babies, tour guides, and crowd noises, so I recommend pulling the clock back to the early morning.