The Bullpen is just outside the Washington Nationals stadium in the Navy Yard neighborhood. It’s easy to go to as the Navy Yard Metro stop is directly across the street.
It’s a great outdoor venue to go and hang out. They host a few different events including food festivals, concerts, and sports watch parties. I went to the Bullpen for a couple of watch parties when the Nationals were on their way to the 2019 World Series. It was the kind of environment that is impossible to replicate. If you weren’t there, you missed out. They also have a special happy hour during baseball games (July – October). It starts at the beginning of the 3rd inning and lasts until the end of the 7th inning of each home game.
Don’t worry if you’re not able to go during baseball season. There are frequent events at the Bullpen every month of the year.