The royal palace of Amber is not just where the royal family lives. The palace is fundamentally the center of government and upper-crust social life in Amber. The first floor of the palace is broadly open to anyone who has a reason to be there — members of the nobility, wealthy members of the merchant class, well-connected Golden Circle types, etc. The upper floors of the palace are more closely guarded, but also open to anyone who has a legitimate reason to be there. Moreover, some of the noble houses have suites within the palace, as do others with significant enough social or political standing within Amber.
Consequently, the palace is a public play space. Although you can scene in the city, note that nearly all characters in the game will have a ton of legitimate reasons to be in the palace for extensive amounts of time, and thus, if you want to run into others in public, the palace is a fine place to do so.
Maps of the Palace
Feel free to report errors and problems with the maps.