The smallest Major League Baseball stadium is Tropicana Field, home of the Tampa Bay Rays. The stadium has a capacity of just over 31,000 fans. That's about 10,000 fewer than the next smallest MLB stadium, Globe Life Park in Arlington (Texas).
Tropicana Field was built in 1990 to replace Al Lang Stadium, which had been the Rays' home since their expansion season of 1998. The new ballpark was originally designed for football and was supposed to be the home of an NFL expansion team that never materialized. As a result, it has a rather unusual layout; among other things, there are large gaps between some of the upper-deck seats and the roof.
Despite its size and quirks, Tropicana Field has been generally well-received by fans and critics alike. It's widely considered one of the best places to watch a baseball game on television (thanks in part to its wide variety of camera angles), and it's also known for having one of the best playing surfaces in all of baseball.