644 Sixth Ave. No. In 1934 H. Holliday was the proprietor. “Good Chili – Best in Two Towns.” On May 18, 1935, the Minneapolis Spokesman carried an ad announcing the opening of the bar’s “Swanky New Cocktail Room (For Ladies and Gentlemen) (No stags admitted to Cocktail Room) Under the Direction of Mr. Duffy Ampey. Drink, dine in the exclusive manner. Keystone Bar Cafe under the management of James Wicks. Liquors, Wines, and 6% beer. Grand opening May 22. In June the cocktail room had been named the Mystic Cavern, not to be confused with the Mystic Caverns in St. Paul.