The Queens Museum of Art in New York City has a scale model of the entire city that is quite astonishing. It's called the Panorama. Built for the 1964 World's Fair, it sprawls 9335 square feet, and contains 895,000 individual building models. It's so detailed that it's been used for ad and movie shoots to fake skyline pans. LegoLand on steroids.
And while there's no scale model of Venice just yet, there is something every bit as remarkable. It's an accurate miniature of the Venetian lagoon, housed in a gigantic facility outside of nearby Padova. Called the Voltabarozzo Experimentation Center for Hydraulic Models, it allows researchers to simulate various tidal and flood conditions and to better understand the impact of different strategies to control inundation and protect the ecosystem. The picture above looks down at the portion of the model that represents the historic center of Venice, and gives you an idea of the mammoth scale of the project.
In addition to the lagoon model, there are also three scaled-down versions of the inlets to the lagoon from the Adriatic at Malamocco, Chioggia and the Lido -- the so-called "tre porti" or three doors to the sea. All these models have been of tremendous aid in the design of the Mose' floodgate system that is being constructed as a means of slamming these doors shut in times of dangerously high water. In fact, there's a mini Mose' housed in the facility, too.
It doesn't look like it regularly allows visitors, but there have been times when it's open for a look. If this sounds like something you'd want to do, try emailing the the Padova Tourist Office at firstname.lastname@example.org and see what happens. Let me know if you do.