Dreams involving large spaces like hotels or airports can symbolize transitions or new experiences in your life. The night setting may suggest that you are navigating through unknown aspects or uncertainties. The act of building small cities in boxes could represent your desire to create order or control in your life, perhaps reflecting how you manage various aspects of your personal or professional life.

The presence of a large dog, particularly a friendly breed like a St. Bernard mixed with a golden retriever, may symbolize loyalty, protection, and companionship. This could suggest that you have supportive relationships or a desire for such connections as you navigate through your current circumstances.

Overall, this dream might be highlighting themes of exploration, creativity, and the importance of companionship as you face changes or uncertainties. Consider what areas of your life feel like they are in transition, and think about the supportive relationships you have that may help you through this time.