"BAR" is a bar in the Trigun series that premiers in episode 4 "Love and Peace". The look of the bar is very basic, even called "A 2-bit saloon" by Stephanie Bostok. Inside is just a few round tables and chairs to sit in and play cards, drink alcohol, etc.
In the anime, BAR was used as a hostage site for Milly Thompson, Meryl Stryfe, Vash the Stampede, Stephanie's butler, and Stephanie Bostok, by a group of bandits. The bar later gets torn up by the group of mercenaries hired by Stan to go inside to get Stephanie and they go crazy.