The center of Charlotte is uptown, and the center of uptown is The Square. That's where Trade Street crosses Tryon, and four city blocks fit into the corners, like the chambers of a heart.

So much happens in these four blocks. Bank of America rises up 60 stories. Michael Jordan sleeps in a condo he bought in December. Bigwigs do deals at the Charlotte City Club. The symphony fills Belk Theater. There's the Booth Playhouse and the King's Kitchen, Ben Long's frescoes and Al Rousso's clock.

The buildings rise high and dive deep, but most of the life is at street level. Here's where Joel the UPS guy has delivered packages for 30-something years. Here's where the woman used to come into Starbucks and take off her clothes. Here's where tens of thousands of Charlotteans - bankers and bike couriers, panhandlers and millionaires - share the same stamp of land every day.

And here at Trade and Tryon, at noon on a Friday, the city at its bustling height, a cop named Charlie Walker strides into the intersection and holds up traffic in all four directions.

After 30 years on the force, and 15 on the uptown beat, he's retiring. It's his last day on the street. And for a moment, he stops the city's heart.

A true investigator

Here's the story Charlie is proudest of. A few years ago, the FBI sent out an alert for someone they thought might have a connection to terrorists. Charlie looked at the photo and saw it was taken at The Square - he knew it was on a Friday because he could see the Green Market cart in the background.

So he started asking around. Someone in the old Wolf Camera store said the man had been in there looking for a bank. A teller at Bank of America said he had tried to cash a check. That led Charlie to a shop where the owner said the man was from Turkey and had sold her some scarves. Charlie asked for an invoice. Then he called the FBI.

"The FBI guy said, 'We had a whole war room looking for this guy, and you gave us a lead in 10 minutes,'" Walker said. "They found him in Florida. It turned out he wasn't a terrorist or anything. But that's what most of police work is to me. Just walking around, asking questions, checking to see what's going on."

Most officers have patrolled by car for years. Even the officers on the other uptown beats went to bicycles or Segways. Walker kept walking. He paced his four square blocks over and over again, never the same pattern in case a crook was watching, sometimes covering 4 or 5 miles a day. (He likes Danner boots and Wigwam socks, and he's in great shape at 52.)

He learned to sense whether someone was dangerous or just distracted. He got to know all the regulars on The Square by name. He arrested lots of people. But he never fired his gun. By the end, he didn't even tote a ticket book.

"Here's how Charlie worked," says Vic "The Chili Man" Werany, who sells hot dogs at Tryon and Fourth.

"One day Charlie's old partner got into it with a buddy of mine... I mean, they were nose to nose. We just knew my buddy was going to get pummeled. But Charlie came over and put his hand on his partner's shoulder and said 'Jimmy, come talk to me a minute.' Then he came over to my friend and put his hand on his shoulder and said 'Chris, come talk to me a minute.' And by the time he was done, the whole thing had simmered down."

On the street with Charlie, people walk up and start giving testimonials.

Gene Muchler, who lives on the streets, comes over to shake his hand: "He respects everybody, no matter what you are or who you are."

Azemeraw Getaneh, a cabbie parked at the taxi stand just north of The Square: "Charlie is a real cop, not a paper cop. He doesn't have to pretend that he's strong."

Cathey Black, a former uptown office worker who runs up to hug him: "He treats people like people."

You learn a few things walking with Charlie. The handrail in front of the First Citizens Bank building used to be great for skateboarders until the owners put bumps in the rail. The sidewalk in front of the bank is a perfect place to take a break in summer, because the doors shoot cool blasts of air. Three of the bronze statues at The Square - Commerce, Industry, Transportation - are looking at the fourth, Future.

Another thing you learn is the proper way to wear a police hat.

Two fingers

He wears one of the first hats he was issued when he joined the force in 1981. He has a new hat, but he thinks the old one is made better. Inside the crown is a folded sheet of paper - a description of those four bronze statues. Visitors ask about them all the time. But now the sheet just keeps his head warm. He memorized the words.

"Two fingers," he says as he puts on the hat. He lays his first two fingers along the length of his nose, and pulls down the angled brim until it lines up exactly. To him, an officer with a squared-away hat is easy to spot and approachable. Charlotte officers generally don't wear hats on the job, but if you walk a beat it's required. And because Charlie was the only one walking a beat, for years he was the only officer wearing a hat every day.

He was born and raised in Charlotte, and after graduating from Garinger High, he did a lot of muscle work - unloading trucks, landscaping, that sort of thing. He never had any interest in being a cop. He remembers being in school and filling out one of those career surveys. One question said: Do you want to work with people?

Charlie checked "No."

But later, when he was working at Pete's Gun Gallery off Albemarle Road, he got to know a few officers. They told Charlie he'd be good at the job. He resisted. Then one day they told him to go out and sit in a patrol car for a few minutes. That set the hook.

After joining the force he rode on patrol a few years, then worked robberies and drugs. But by 1996 he was a single dad, raising a young son, and he wanted more stable hours. His boss said there was an opening on the uptown beat, 7 a.m. to 3 p.m. (the shift is now 8 to 4).

Charlie remembered his grandparents taking him uptown when he was a kid - if he was good, they'd buy him green sherbet at the Belk cafeteria. But he hadn't spent much time there in years.

"It was mainly for the hours when I first took it," he says. "But pretty soon I saw the advantage of it was the freedom of being out of the car and talking to people. I saw that I could put a little bit of my personal touch in it."

Some things he couldn't talk through. One day a guy clocked him from behind with a sack full of canned goods. Another time a guy with a stick wouldn't put it down, and Charlie became the first officer in the city to use his Taser.

But he laughs at most of the memories. The naked guy who showed up in front of the Baptist convention. The man who opened up his guitar case to reveal a frozen squirrel. The judge who chewed him out because he thought Charlie was calling a suspect a "street creature," when Charlie was saying "street preacher."

He shook Magic Johnson's huge hand and saw Billy Graham's hair blow in the wind.

He watched the yearly uptown Christmas tree go from real to artificial.

Sometimes it's hard not to feel that Charlotte has gone the same way, real to artificial, that our city is so big and so diverse that there's no way to get to know it.

But then there's Charlie Walker, who walked the same four blocks for 15 years, befriending bankers and cabbies and homeless men, getting to know his little part of the world one face at a time.

"It's an amazing gift," says Earl Gulledge, a recently retired real estate project manager who worked uptown. "With the uniform, he represents authority. A lot of people haven't had good experience with authority. But with Charlie they get time, and respect, and a little conversation. He's a good police officer. But he is also a person of kind spirit."

Charlie is not going completely away. He has moonlighted for years doing security at Bank of America headquarters. He has also applied to stay with the police department as a reserve officer, filling in an occasional shift. He hopes to walk his old beat one or two days a month.

He worried that other officers don't respect his methods. He thought for years that his replacement would take a bike or Segway, and that he'd end up being the last Charlotte officer to walk a beat.

But then he noticed a couple of other uptown officers had decided to give walking a try. And then his boss told him the department planned to fill his job just the way it was. Officer Michael Cucinella - everybody calls him Cooch - would be Charlie's successor.

Charlie's last official day is Feb. 28, but the department put him on desk work for his last couple of weeks. He found out just a few days in advance about his last day on the street.

He called a few friends, and told them to come to The Square at noon.

The change of command

They came. There's the retired maintenance men, and the women from the company that manages the Independence Center. There's a couple of friends from Fourth Ward, and there's Charlie's old partner, Jimmy Horne. There's Gene from the streets, and Ronnie, who is known for his loud, unsolicited weather reports. Charlie has assured Ronnie that he can still have that job.

There must be two dozen people who came here for Charlie. But it's noon on a workday so the sidewalks are full of people, the richest and the poorest, the immigrants and natives, the beating heart that Charlie Walker protected for 15 years.

He walks out into the intersection and stops the traffic.

Officer Cucinella comes out behind him.

They face each other on opposite sides of the manhole in the very center of the intersection.

"Mike Cucinella," Walker says, "I've had this Square for 15 years. It's now under your command."

"Thank you, brother," Cucinella says. "I'm going to salute you now."

He does, and Charlie salutes him back.

They walk to the corner, and wave their arms, and in seconds the traffic is flowing and people are streaming through the crosswalk.

It happened so fast that if you had passed through right at that moment, you wouldn't have noticed anything different in the center of the center of the city.

Except for all those people, in all four corners of The Square, still clapping for the man in the hat.