Forty years ago last week, our favorite asphalt metaphor opened.

On Aug. 17, 1964, the two ends of the Capital Beltway were knitted together just east of New Hampshire Avenue. A caption for a photo of the Beltway in The Post that day noted: "It has no stop signs or traffic lights." Like a Mobius strip or a wedding ring, it just keeps on going.

Some people hate the Beltway -- won't drive on it. But it's no use hating something that is so much a reflection of us, such a strong thread in our region's fabric of identity. So, while it's not exactly hiking the Appalachian Trail, I decided to mark the Beltway's birthday by driving the circumferential highway's entire 66-mile length.

It's 9:05 a.m. on Wednesday as I roll onto the outer loop of the Beltway at Route 29/Colesville Road. A truck is stopped on the right shoulder, its hood open, traffic triangles out behind it. Traffic hasn't backed up yet, though, and we are speeding along quite nicely. If you're going to drive all the way around the Beltway, a mid-morning in late August is the time to do it.

At places along the Beltway, you can feel like a BB in a chute, so high are the noise barriers, those towering walls that try to tame the road's surflike noise. A highway official once told me that the Beltway's first sound walls went up at Georgia Avenue. Those original ones are long gone, though, and the ones I pass now are descendants. (Those metals doors cut into the walls? Locked, in case you were wondering.)

At Connecticut Avenue, I pass first a tractor- trailer carrying a container decorated with the Arabic script of the United Arab Shipping Co., then a white Chevy truck pulling a horse trailer with a tiny pony inside. The Beltway must be the most egalitarian place in the area, better even than the Metro for bringing together rich and poor, black and white, commuter and tourist, trucker and soccer mom. Of course, we don't actually rub elbows; fenders, sometimes.

I cross the Potomac over the American Legion Bridge -- a bridge I've always found vaguely unsatisfying, since you can't actually see any water as you go over it -- and then things start to slow. At Exit 44, Georgetown Pike, I encounter that typically maddening Beltway pause: no discernible reason, no mention on the radio, no idea whether you'll creep along for 30 seconds or 30 minutes.

In this case it's the former, and soon we are on our way: VW Cabriolet, Toyota Camry, Ford F-250 Super Duty, all of us spinning counterclockwise. I pass a tractor-trailer carrying a tractor-trailer (an arrangement I've always thought looked kind of weird, like a pair of dragonflies mating).

I look to my left at Arlington Boulevard and see that the inner loop is backed up. There is nothing more queasily satisfying than seeing the other loop of the Beltway backed up. "Those poor suckers," you mutter, knowing full well that it won't be long before you're the yin to their yang, a poor sucker yourself.

At Braddock Road, a Mazda and Toyota are pulled over on the left shoulder. They're having a little adventure, the only bright side of which is that they'll have a story for the rest of their lives: the day I broke down on the Beltway.

The Beltway's like a coral reef that way, littered with shipwrecked motorists and bits of assorted detritus. I swerve to avoid a piece of plywood. On the shoulders are fragments of truck tires, the broken lid of a foam cooler, plastic bottles, what appears to be a catalytic converter. All in all, though, it's remarkably clean.

Just past the Springfield interchange, flashing arrows order me to the left. The right lane is closed ahead, and I pass the man with the scariest job in Washington: putting the traffic cones out on the Beltway.

Then I come to this sign: "Drawbridge 5 Miles." The incongruity suddenly strikes me as funny. You're on this massive highway, and you come to a sign for something out of medieval England.

And then I'm on the drawbridge. The view is nice from the Wilson Bridge. You actually can see some water. A boat is zipping along the river. Just to the right is the new bridge aborning. Painted on various girders are the words "East" and "West." As they say, measure twice, cut once.

Maryland welcomes me. A big helicopter leaving Andrews Air Force Base flies over, leaving a greasy trail in the sky.

Traffic is doing close to 70 as I book past Landover Road. A road crew is working in the median strip, muscling silvery guardrails into place. The long ribbons of steel glint in the sun.

As I near Route 450, a white car darts in and out of traffic, nipping back and forth from the far left lane to the second from the right. He's trying to get that tiny little advantage that will get him there just a little sooner, wherever it is he's going.

With nowhere to get to and plenty of time to get there, I'm in no hurry.

Maybe that's why when I get back to my starting point of Colesville Road and I look at the clock, I see that it has taken me a mere 61 minutes to circumnavigate the Beltway.

I get off, turn around and drive back in the other direction.

Ring Around the Rosy

I have a friend who once walked on the Beltway. Traffic was completely stopped, and people were getting out of their cars to crane their heads and look ahead.

He said it was really weird to actually set foot on something he'd only ever driven on before. He expected the pavement to open up and swallow him.

What experiences have you had on the Beltway? Share your inner or outer loop anecdotes with me. E-mail them, with "Beltway" in the subject line, to kellyj@washpost.com, or mail them to John Kelly, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071.