A wealthier, more civilized planet relatively close to certain border worlds. Serenity was headed to this planet before the ship's steering was sabotaged by Saffron in Our Mrs Reynolds. Mal described it as 'A decent sort of planet', whose prime industries are 'factories and the like. Some ranches, if you're more for the outdoors...'
As seen in the Serenity Movie, cities on Beaumonde seem to be heavily populated and industrialized, akin to the cyberpunk version of Hong Kong in Deus Ex.
New Dunsmuir is the capital of Beaumonde. The city is the only planet that has no factories. Located on an ocean, New Dunsmuir is a popular tourist attraction.
The Maidenhead is a bar where the crew have their meeting with Fanty And Mingo.