There is a Mark Twain Room in the Fox Brewpub in the brick St. Charles Hotel (Built in 1862) in Carson City Nevada. There have been various restaurants there since the hotel first opened. 
 To be technical, the north wall of the room was an exterior wall of the hotel itself, and the restaurant (with bar) that Twain visited was on the other side of that wall. The small (capacity for meals 18) private dining room features images from Carson City when it was in Nevada Territory (1861-64) and a plaster cast of Twain.
In a message dated 6/5/2023 6:45:07 AM Pacific Standard Time, [log in to unmask] writes: 
Odd question for the group. What diners and restaurants are you familiarwith that build their branding around Twain and/or his characters? Someexamples include Huck Finn's Donuts in Chicagoland, Tom Sawyer's in BocaRaton, and Aunt Polly's Pizza in Indianapolis. Interested in both currently operating and defunct establishments. If you happen to know what year it opened, please include that as well. *Matt Seybold, PhD*Associate Professor of American Literature & Mark Twain StudiesScholar-in-Residence, Center for Mark Twain StudiesEditor, MarkTwainStudies.orgHost, The American Vandal Podcast<https://marktwainstudies.com/the-american-vandal-podcast/> Peterson Chapel Vestry, Cowles [log in to unmask]<https://www.elmira.edu/>