As CBS News Correspondent Jim Stewart reports, it used to be you would ride from place to place, get off, take a tour and catch the next trolley.
Only ever since Sept. 11, as most tourists are learning, you might as well just stay on the bus.
The Capitol Building is left out of the tour, as is the White House.
"The people's mansion is closed off to the people forever more," says the trolley operator.
Oh, you can still see it. It's behind a plastic sheet and cyclone fence right across what used to be Pennsylvania Avenue, which is now being turned into a truck-bomb-free pedestrian mall.
The Washington Monument is also getting an anti-truck-bomb girdle. At the Capitol, a visitors' center is taking shape that looks suspiciously like a bomb shelter. Tourists will enter the building through an underground tunnel and view the dome through a skylight.
And to even get that far, if police have their way, you would first have to pass through a guarded fence around Capitol Hill.
"We are concerned about the non-passive suicide bomber," says Capitol Police Chief Terry Gainer.
The fence is Gainer's idea, and he's not kidding.
"What you don't want to do is fight the battle on your front door steps," says Gainer.
And that's not all. If Gainer gets his fence, he said he'd next like a tunnel that would burrow deep underneath Capitol Hill and reroute all the traffic.
Architects call it "security creep." From bollards to barriers and ugly guard shacks, the city looks like it's under siege. And the people in charge of keeping Washington beautiful, like Richard Friedman of the National Capital Planning Commission, are sounding a little frantic.
"After Oklahoma City and after Sept. 11, there have been reactive things and people are in fear," says Friedman. "We've gotta calm down. These are the public streets. This is the public realm."
Or at least it used to be.
As tour operator says: "You can walk right up to the fence, all the way around the fence, just do not climb the fence. Welcome to the White House."