Possible Clues:

• Curly-leaved cabbage
• For example, very old packed theatre
• London luxury hotel that opened in 1889
• "The Heartbeat of Harlem," per Langston Hughes
• Hotel, for example, housing 50?
• Alpine duchy of yore
• Beatles "___ Truffle"
• Theater that showcased Gilbert and Sullivan operas
• Type of cabbage — London theatre
• London theater at which "The Mikado" premiered