A city laced with waterways, criss-crossed by rivers and canals controlled by ingenious technical devices. A surprising new Milan is on display at the "Museo dei Navigli" (Museum of the Waterways) on Via San Marco, which is near the site of a XVIth century lock - still in plain view - used to regulate water flow long ago. The Museum's exhibit rooms host a variety of frescos depicting various aspects of life on the Waterways of Milan and the city's history. Ever since Roman times, as a matter of fact, Milan has counted on an impressive number of Waterways for a variety of practical functions. Their main role was in cargo transport - the marble used to build the "Duomo" (Cathedral), for instance, came from the Candoglia Quarry on Lake Maggiore.