There are 72 steps in the steeple of St. Mary's Church in Chinatown. They twist in an impossibly tight spiral that turns counterclockwise as you ascend.

Early Sunday morning, just as the sun was doing its own climb into the sky, I followed Don Clark up the stairs, the curved walls seeming to press in on us as we trudged higher and higher. A knot of keys jangled at his waist, near a tape measure that was clipped to his belt and a Swiss Army knife that was snug in a little pouch.

Sixty-nine, 70, 71, 72. Finally we were there and could catch our breath as we gazed at the reason for our exertions: an artful arrangement of gears and pulleys and weights that since 1920 has told anyone who walked down the street what time it is.

The clock in the St. Mary's steeple is about the size of soda machine turned on its side, or smaller even, but open, exposed like a fleshless skeleton, its toothed wheels looking almost delicate. Its iron frame is painted green, with gold striping. A tiny plaque reads: "Made by Seth Thomas Clock Co. Thomaston, Conn. USA. No. 2158. Dec. 21, 1920."

"So it rang for Christmas," Don said.

Don, 62, has been taking care of the clock since 1971. He repairs old pipe organs and after working on the church's 1893 instrument asked if he could practice on it. The pastor said sure, and why don't you play it every Sunday? Now Don is the church's music director, driving in from his home south of Front Royal, Va.

And he's the clock guy. A couple of times a year he climbs the steeple to check on things, oil the gears and, as he did Sunday, to change from daylight saving time to Eastern standard time, or vice versa.

He had stopped the clock for an hour. Now it was time to start it again. He pushed the pendulum, which hung down like a yardstick from the clock's movement, and the bob at the bottom began swinging back and forth like a massive, cast-iron salami. The stone chamber was filled with a reassuring tick-tock tick-tock.

"All right," Don said. "It's good until next spring."

Then we climbed higher, up some rickety wooden ladders that took us to the tower's clock face level. Four frosted glass dials are set into round holes in the steeple. A rod from the mechanism below pierces the middle of the floor. Connected to it are the universal joints that convert the vertical motion of the clock to the horizontal motion needed to turn the hands.

This looked like a good place to have the denouement of an action movie.

Next it was up to the belfry. (Don has never had bats in his belfry. Pigeons, however, are another story.) The four bells -- forged at the McShane Foundry in Baltimore -- ring every quarter hour from 9 a.m. to 9 p.m. Don has things set up so the clock is silent the rest of the day.

"Before the hotel was built I used to let it strike the hours at least, all night long," he said, referring to the Red Roof Inn across the street. "We don't anymore. I think it would disturb people in the hotel."

St. Mary's was built in 1890, to serve Washington's German Catholic community, who had tired of taking the train to Baltimore to hear a Mass in their language. It still offers services in German, along with English, Latin, Cantonese and, once a month, Hungarian.

The bells that have chimed for 84 years don't need any translating. Time to pray, they say.

I ask Don what he thinks the neighborhood was like back when the clock was installed, about 30 years after the church opened.

"It would have been so much quieter," he said. "There would have been only a few automobiles, and the streetcar. There would have been horse-drawn carriages. There were houses all over the area. I think people would have depended on the clock to know what time it was. . . .

"Just be happy it's not striking right now," he added as we stood in the belfry. "It's rather deafening."

We climbed down and then drove a few blocks to see another clock Don maintains.

We arrived at St. Aloysius on North Capitol Street just as a bell rang twice, marking 7:45 a.m. "That's what they call a ting-tang," said Don.

"This is much cruder," he said of the St. Aloysius movement. "This was a homemade clock so to speak," built by a Jesuit brother in 1860 using what's called a three-legged escapement.

Don twisted a gear at the front of the clock, turning it back an hour, then adjusted the chiming mechanism.

"To think that this has been here for, what -- 144 years? -- with minimal maintenance is really quite remarkable."

We clambered up another ladder, squeezed through a trap door and were at the belfry, which at St. Aloysius is open, with no railing or parapet to keep you from plummeting to the street below.

I heaved myself through the opening and queasily grabbed onto a column.

"And there's the world, spread out for everyone to see," said Don.

There was Mount Airy Baptist Church across the street, and St. Phillips Baptist Church near it. On the horizon were the Washington National Cathedral and the Shrine of the Immaculate Conception. You could see the spires of All Souls Unitarian Church on 16th Street, the steeple of the Church of the Ascension and St. Agnes and the red dome of the old Adas Israel synagogue.

"You used to be able to see St. Mary's," Don said.

I imagined the two churches, their bells calling out to the faithful, and to each other.

To take a video tour of the St. Mary's steeple, go to www.washingtonpost.com/metro.