Ever bothered walking underground for the hell of it? You can foot it from the Gallery to the Philadelphia Sports Club at 18th and Market without once surfacing for fresh air. No waiting involved. The route is often smelly, yes, but it comes in handy on cold and rainy days, and as luck would have it, it's been pouring buckets all afternoon. The train moves on.

The Eighth and Market station is undergoing renovations right now, so exposed piping and decayed bits of ceiling dangle here and there. According to one orange sign posted near the westbound El, the work will continue until Aug. 8, 2007. A man sells flowers in front of a dingy, translucent plastic sheet being used to hide the construction. Another man furrows his brow as he attempts to ease a dollar bill into a SEPTA token machine. A line forms behind him.

Just beyond a set of double doors, kiosks shaped to resemble prairie wagons display stuffed animals, keys, T-shirts and assorted bling. Three girls emerge from the Foto Fantasy grinning and giggling. I buy a soft pretzel and a smoothie and walk west into the Gallery.

It is difficult to not eat on this bottom level. The Food Court dominates the area, its outskirts populated by older folks sitting in big groups, chatting and casually sipping sodas. Farther in, young'uns eat with purpose, surrounded by shopping bags. Even after you exit the Food Court, one-word neon signs (chicken! pizza!) point out additional eateries along the way. I sample some salty thing in a paper cup and continue on my way.

Market East Station appears suddenly to the right. TV monitors dot its walls, and people perched on oversized cubes stare at them. Two men sit at a table topped with many copies of L. Ron Hubbard's Dianetics . I accept their free stress test, and Charles, a 70-year-old construction worker with dirty fingernails and stale breath, instructs me to put down my drink. After vigorously rubbing my hands between his (he explains that they need to be warm for the test to work, and I make a mental note to wash my hands), he gives me two metal cylinders, which are hooked up to the stress machine. Gripping the cylinders, I think about life, and the little needle inside the machine moves to the right or left, depending on whether the subject stresses me out (right), or I'm in denial that the subject stresses me out (left). Charles tries getting me to name people that I hate, but I can't come up with any. The needle moves to the left. We half-heartedly discuss jobs and friends before Charles pulls out the literature. "Did you know Tom Cruise couldn't read or write before he discovered Scientology?" he asks.

Across the corridor, before the entrance to the 11th Street Market-Frankford Line, two boys hold out Slim Jims and candy. I pull open the doors and get hit by a wave of muggy heat. A train rolls up, but instead of boarding it, I walk alongside it in the pedestrian concourse. SEPTA and I kinda feel like kindred spirits this way — we could almost hold hands — until the train speeds away. The concourse is not air-conditioned, and the heat worsens. Fluorescent lights buzz overhead. A train rumbles somewhere. I concentrate on sniffing the air, which smells of urine and, oddly enough, skunks.

Just after 13th Street I hit the first fork in the road. Onward to the west, or turn right into the poorly lit City Hall Annex? I choose the latter, which turns out to be a desolate, winding corridor with ketchup-colored stains on the wall. A thin stream of yellowish liquid runs along the floor. It occurs to me that if I die along this stretch, there's a good chance nobody will find me for days. The annex spits me out at Broad and Arch, where a man in white snoozes on a bench. I backtrack in a quick trot, toward the Broad Street Line, followed by a stop at the fountain and big napkin-looking sculpture in City Hall's Dilworth Plaza.

It is raining hard now, so I stroll through the circular concourse surrounding the plaza. A few guys hang out on lawn chairs and on the floor. One relieves himself against a wall. His friend says hello.

At this point, things get hazy. At the heart of the Center City transit system, City Hall has lots of veins and arteries popping out of it, and without the help of street signs, navigating this bit of underground highway can be disorienting. Every turn I take, I reach a staircase with a vastly different view of City Hall. After wandering for a half hour, I wind up at the giant clothespin at 15th and Market, where a small crowd has formed in the Dunkin' Donuts. People without umbrellas gaze out at the showers.

Past the El, past the shoe repair shop and another Dunkin' Donuts, through Suburban Station. More people sitting. More people waiting. Some SEPTA workers shovel water out of a flooded stairway exit. The rain stops momentarily, and I bound up the steps to 18th and JFK. The sun's not out, but I squint anyway. Then I head back down to catch the next train home.

(tami.fertig@citypaper.net)