Venice has installed temporary gates at the ends of two bridges to turn back tourists if their numbers become overwhelming.
The Italian lagoon city put the measure in place for a four-day holiday weekend that ends on Labour Day, May 1.
By early Saturday afternoon, municipal police officers monitoring the flow of arrivals judged the crowds manageable enough that the gates didn't need to be shut yet.
Tourists far outnumber residents in carless Venice, where the narrow streets become almost impassable during peak travel times.
Crowds get especially heavy when cruise ships disembark thousands of passengers at once for day trips.
The city has struggled for decades with what to do about its dwindling population, but also lives off tourism.