Then the groundskeepers took away the red velvet "cathedral" on which Pope John Paul II sat.
The orange and purple chrysanthemums disappeared soon after that, followed by rolls of sod and folding chairs and vestments worn by visiting cardinals.
Within hours after the end of the outdoor Mass at Oriole Park, a small army of landscapers and others had descended on the temporary altar site to make it look like an outfield again.
Many of the liturgical objects used on the altar were borrowed from the Basilica of the Assumption and will go back there this week.
Other items, such as the waist-high partitions around the papal chair, were struck the way a theatrical stage set is taken down after a show's final performance.
Representatives of the Maryland Stadium Authority, the ballpark's owner, said they were pleased with the smoothness and swiftness of the cleanup.
"It's going fine," said Ed Cline, deputy director of the stadium authority. "We're not aware of any problems."
By early evening, crews had removed most of the altar and the flooring area set up in the outfield of Oriole Park. The 33-foot-high cross was due to be moved this week to its permanent home, the Catholic Relief Services headquarters on West Fayette Street.
Sherman Kerbel, director of facilities for the stadium authority, said the 50,000-plus worshipers left the stadium cleaner than it is after a typical ballgame.
"Don't forget, we didn't have peanuts and we didn't have beer, and no vendors were allowed in the seating area," he said.
Mr. Kerbel said his chief concern was the condition of the grass that was covered up by the altar and the flooring for more than 24 hours. The material was a lightweight flooring system called Terraplas, which is designed to let ultraviolet light through to the grass underneath.
As the first panels were uncovered, the grass looked flattened but still green. The Orioles' head groundskeeper, Paul Zwaska, said he would wait until today or tomorrow to make a final determination. He said his main concern was with the area under the altar, since that was covered by more than the Terraplas.
"A couple of days of watering it and mowing it, and it'll bounce back," promised Mike Titus, a representative of Foxboro Stadium, which owns the panels and rented them for the Mass. "It'll be fine."
Outside the ballpark, meanwhile, the cleanup went just as smoothly.
More than 120 employees from Baltimore's Department of Public Works reported for duty yesterday to get the city back in shape for this morning's rush hour. By 5 p.m., most of the orange crowd-control fences were down and crews were sweeping the streets.
George Balog, director of the city's public works department, said the crowds dispersed quickly, and that helped the cleanup crews stay on schedule.
"Our goal is, when people come to work on Monday, to make it look as if nothing happened," he said.