It was the thrill of a lifetime for maintenance worker Gregory Walton, who shook hands with President Barack Obama Thursday night at Phipps Conservatory and Botanic Gardens during the first day of the G-20 summit.

Mr. Walton wasn't supposed to be working on a panel that controls the fire alarms, but his boss got called away. While standing by the panel early in the evening, the president walked out of the restroom in the welcome center.

"He saw me, made eye contact and walked straight over to me," Mr. Walton said. They shook hands and the president said, "I'd like to thank you very much for the great job you've done."

Mr. Walton was thrilled and immediately started texting his 18-year-old daughter Jasmine to tell her the exciting news. Then he got on the radio to call his boss, Scott Benack, and by the end of the night the rest of the 12 Phipps staff members on duty had come by to congratulate him.

The whole encounter lasted only a minute, but it's something Mr. Walton will never forget.

"I was shocked, I was surprised, you can tell he shakes a lot of people's hands," he said with a laugh, referring to the president's firm grip. "It was a proud moment for me. I voted for him."

But he wasn't the only one who met Mr. Obama. Phipps' executive director Richard Piacentini, his wife and two children welcomed the president and first lady Michelle Obama to the conservatory and were photographed together. He then presented them with a glass bowl and some glass frogs created by artist Hans Godo Frabel, whose work is currently on display at Phipps.

Mr. Piacentini, who is also past president of the American Public Gardens Association, gave Mrs. Obama a commendation from the organization to recognize her work with gardens, children and promoting fresh food.

Mr. Piacentini and his staff were stationed around the conservatory to guide the dignitaries and answer their questions. "To have all these different people from around the world going 'ooh and ahh' with big smiles on their faces, it was a great experience. It was one of the most important parties ever and it happened here at Phipps," he said proudly.

Mr. Benack, facilities manager at Phipps, said he had his own encounter with the world leaders. He sat on a wall in the Tropical Forest for more than an hour just outside the glass doors of the special events hall where the leaders had their working dinner.

"It was a surreal moment, he said, I was 10 feet from everyone. I could look in and see the German chancellor, President Obama, the president of Italy. It was pretty interesting," he said.

He was surrounded by security, assistants and aides in the shadow of tall tropical trees. "I couldn't believe I was allowed to be that close." He even got a chance to take a few pictures.

Margie Radebaugh, Phipps' director of horticulture and education, was stationed in the Japanese Garden and got a chance to peek over the balcony of the welcome center to see Mr. Obama before returning to the garden.

A light rain kept visitors sparse in that garden, but French President Nicolas Sarkozy and his wife Carla Bruni-Sarkozy braved the elements to stroll through the outdoor space. Mrs. Radebaugh heard the first lady utter "ce magnifique" as she entered the garden. That brought a smile to Mrs. Radebaugh's face.

"We think it's magnificent," she said, laughing, "but it was pretty cool to hear it in French."

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