You can spend a few hours each night surveying the city. From your observations and investigations, you are able to learn from the following: locations of key places in the city, such as jails, armories, barracks, banks, etc; guard rotation schedules; locations of places pertaining to organized crime, such as taverns, fighting rings, clubs, alleyways, etc; names and faces of government officials and their assistants, either corrupt or upright; names and faces of crime lords, henchmen, thugs, and criminal informers; and many more potentially helpful pieces of information. This time may also be spent fighting crime, interrogating suspects, or going undercover. If you spend more than three hours on your investigations, you do not gain the benefits of a long rest overnight, but you may still gain the benefits of a short rest depending on how your time is spent. If you do not spend at least one hour sleeping, you gain one point of exhaustion. When you are not using this feature, you still require the standard 8 hours to gain the benefits of a long rest. Work with your DM to determine how much you are able to learn, and how much active play is required for these parts of the story.