Buy tickets to see a game at San Manuel Stadium. If there's nothing on while you're in town, you might like to check if they give a guided tour of the facilities.
This sporting facility is on the to-do lists of many visitors to San Bernardino. But San Manuel Stadium isn't the only drawcard here. Yaamava' Resort & Casino, California State University San Bernardino, and San Bernardino Soccer Complex are some other interesting sights nearby.