RPM is the acronym used for revolutions per minute. It measures the number of revolutions completed in one minute around a fixed axis, giving the speed of a mechanical component. It is commonly used to describe the performance of automobile engines.
Like most ballparks built from the 1990s onward, Safeco Field is a 'retro-modern' style ballpark that incorporates many of the features of ballparks built in the 1950s and earlier with modern amenities.
Built in 1914, Chicago's Wrigley Field is known for the ivy growing on the outfield walls. It was planted in 1937 under the supervision of baseball innovator Bill Veeck, who worked for the team at the time, for aesthetic value. The ivy has become an attraction at Wrigley Field, much like the Green Monster in Boston.