Starting next summer, Philadelphia will require licenses for private tour guides operating within its historic district—which is, roughly put, the square mile around Independence Hall and the Liberty Bell.

The law requires guides—whether on foot, buses, trolleys, or horse-drawn carriages—to pass a written test and be re-certified every three years. (The National Park Service rangers who work inside Independence Hall and the Liberty Bell aren't affected by the rule, though. NPS has its own training requirements and quality-control checks.)

I recently met with Philadelphia tourism officials, who were buzzing about the legislation, which mayor Michael Nutter is expected to sign this Thursday. Once the program is running in little more than a year from now, the city's tourism website gophila.com plans to list the companies with certified guides.

Philly's exam, which will cost $25, hasn't been developed yet. It will be written by a group of tour operators, historians, and university professors.

After two years, the City Council plans to review the program and will likely expand it beyond the historic district. Many of the city's attractions, such as the zoo and museums on Ben Franklin Parkway, fall outside of the regulated zone.

Now if only Philly’s newly minted experts settle the debate of who makes the best cheesesteak! (For details on this debate, turn to the blogs at PhillyBurbs.)

Philadelphia isn't the first city to require that its tour guides be licensed. Charleston, New Orleans, New York City, Savannah, and Washington, D.C.,—and cities overseas, such as Rome—already license their tour guides.

Do you think this law will help prevent tour guides from embellishing history? Should every city enact similar legislation?