The oldest ballpark in North America is Fenway Park, home of the Boston Red Sox. The newest, Globe Life Field in Arlington, Texas is home of the Rangers.
What does one have that the other does not?
The answer is a retractable roof.
It's a small group of architecture that Milwaukee has had the luxury of knowing for 20 years. If you are a sports fan, it may be one of the more important rooftops in the state.
For American Family Field and the Milwaukee Brewers, it's not just Opening Day that can bring some frigid temperatures. From the end of March to late October, Mother Nature can throw some serious curveballs.
It is rare to have games completely scratched off the schedule due to weather, but without a roof, fans are vulnerable to the dreaded rain delay.
The longest rain delay on record, the 7-hours and 23-minutes Chicago White Sox fans faced in 1990.
Plus, while the frozen tundra is a magical place for football, seeing bats literally go cold is not ideal.
No surprise that the Toronto Blue Jays were the first in MLB to put a retractable roof over the diamond.
Today the Arizona Diamondbacks, Houston Astros, Miami Marlins, Seattle Mariners, Texas Rangers, and of course Milwaukee all have retractable roofs. In Tampa, Tropicana Field's roof is a permanent fixture.
As old fences are replaced throughout time, it makes sense to have some options. Meaning, American Family Field might not be the only North American fan-shaped convertible roof for long.
What it will always be, is a great and dry place to play ball.