In New York, nothing draws a crowd like a crowd. Sidney Giustra has lived a block south of the World Trade Center for 17 years, long enough to know when someone famous is arriving. She went outside to find Robert De Niro, George W. Bush, Joe Biden and Andrew Cuomo.
Each time, the impending arrival is announced first by police commanders standing around in white shirts, and then by a much larger crowd of onlookers with their smartphones at the ready.
That observation came in handy for Ms. Giustra on Tuesday afternoon, an hour before Prince William arrived for a tour of Ten House, the fire station famous for its response to the Sept. 11, 2001, attacks.
“I knew he was coming downtown,” said Ms. Giustra, 52. “But then I saw the crowd and thought, yeah. He has to come here.”
Only a few people in the neighborhood seemed to know about the prince’s visit beforehand. Ann Donnelly was alerted by police officers in dark suits and serious faces who gathered in the middle of Liberty Street.
“Really? Prince William? Cute,” said Ms. Donnelly, a tourist from Fort Myers, Fla. “Well, I have to hold out for that.”
Tara Pozza took the bus from Scranton, Pennsylvania, on Tuesday morning to spend a day in the city. By 3 p.m., she had already toured Madison Square Garden, the Natural History Museum, an art gallery in SoHo and the 9/11 Memorial Museum before she spotted the crowd near the firehouse.
“My goodness. And I chose to come to New York City today?” Ms. Pozza, 39, said. “I’m so happy!”
The crowd grew to about 700 people. Among them were Lesleyanne Pearson and her husband John, tourists from England who tried to catch a glimpse of the royal family at Queen Elizabeth’s Platinum Jubilee in 2022 by standing behind Buckingham Palace for hours.
They failed. Now, in New York City, they were determined. They arrived early and secured the best spot, front row, next to the photojournalists’ campsite. Mr. Pearson was holding his phone. His wife was carrying a digital video recorder with the viewfinder open and ready to use.
The Pearsons are fans of the royal family. They’re not so impressed with Prince William’s mission in New York to promote the Earthshot Prize, his charity that awards millions of dollars to entrepreneurs with ideas to reverse climate change.
“To demonstrate his environmental credentials, he flew here across the ocean,” said 72-year-old Mr. Pearson. “Right.”
A few minutes before 4 p.m. the prince arrived in a dark gray Range Rover. The crowd was quiet except for a few cheers.
“I’m in awe, so to speak. I’m ready to cry,” Ms. Pozza said.
William shook hands with Laura Kavanagh, the fire commissioner. Together they walked around the corner to see the fire department’s 9/11 memorial.
“I should have stayed home,” Ms. Giustra said. “I could have seen him better from my apartment.”
Williams’ tour continued inside the firehouse, protected from the crowd by a metal barricade and two rows of police officers.
A New Yorker managed to get much closer: a gray rat, long but not particularly fat, scurried across the entire block of Liberty Street and nestled on the curb. The rodent reached the front of the firehouse, found a sewer hole and jumped in.
Everyone cheered. “Yay! Go!” exclaimed Mrs. Pozza.
A few minutes later, William walked across the street to joke and shake hands with people in the crowd. Jose Cabrera, a tourist from Chile, became nervous.
“What should I say when I talk to him?” Mr. Cabrera said. “‘Your Highness’? Is that correct?”
New Yorkers were not easily intimidated. Isabella Ward is 22 and lives in Manhattan. For a moment she felt crushed. The crowd behind her grew. The great prince loomed directly in front of him. William stuck out his thumb and pointed at his security guards.
“I’m sorry, but I have to go,” he said.
Ms. Ward wasn’t having it. She asked for a selfie. The future King of England paused. He turned around, crouched forward, and smiled into the phone. Then he went back to the Range Rover.
Ms. Ward also turned away from the crowd. She leaned over her phone, eager to text the picture to her mother.
“That was cool,” she said. “I was not expecting that.”