But the multi-purpose stadiums — and the "cookie-cutter" subset of such — were doomed to fail, Smith said, because they simply tried to do too much. The seats could never be configured to provide the proper sightlines for both football and baseball. And as the way fans hoped to experience game days for football and baseball evolved, owners found it difficult to renovate stadiums in a reasonable way.

Camden Yards and the parks it helped inspire should have more "elasticity," Smith said, because the focus is narrowed.

"They really are living, breathing things, these stadiums," said Smith, who played an important role in changes made to Turner Field in Atlanta and Fenway between her stints with the Orioles. "And reaching our 20th year seemed like a significant point — just as when you reach that point in your life. We feel like now we can reflect on our history more. We're old enough to celebrate."

The Orioles will erect six statues honoring the five players and one manager whose uniform numbers have been retired, and they have decorated the concourse with previous team logos. That they'll need to continue these sort of aesthetic upgrades is a given. The team also worked to improve concession areas because food preparation methods and fan tastes have evolved.

Other future changes aren't so easy to envision. Technology will change the way fans experience games, as scoreboards become even larger and more elaborate. Rosentraub sees a day when teams will make special accommodations to help fans follow their fantasy teams, and some clubs are already allowing patrons to order food via phone or tablet and have it delivered to their seats.

Luxury suites — the high-revenue-generating areas that pushed many owners to fight for new stadiums — are being rethought, as well. Many teams are contemplating using those areas for child care, Rosentraub said, or gearing them toward the whole family; mom and dad could watch the game while the kids have space to play nearby. Other suites will be redesigned to better host events.

"People will come for a party," he said. "The baseball game will be secondary."

Having just recently finished a major overhaul of the Orioles' spring training facility in addition to the tweaks of Camden Yards, Smith said there were no major projects planned. A spokesman for the Maryland Stadium Authority, which owns the stadium, said that it was not that agency's job to speculate on future land use.

But Joe Spear, one of the original architects of Camden Yards, felt all along that the stadium would last for exactly as long as the people of the city wanted it to.

"If you do something that's perfect for Baltimore in Baltimore," he said, "it's going to live forever because people will love it and take care of it."

chris.korman@baltsun.com

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Baltimore Sun reporter Peter Schmuck contributed to this article.