A man's home is his castle. In some cases, a man's castle is his castle. In those cases he's allowed to color whatever color he wants. Including yellow, red, and blue like the castle in today's poster. D&D hasn't had castle building for a few editions now which is a crying shame. The party will really feel at home if they have their own base of operations. A few mechanical benefits will tend to seal the deal on any base you give them. ie protection circles, extra rest benefits, etc. It has side benefits for you as a GM. The party has a central location that adversaries can discover. Said adversaries can attack the base while the party is away to make any feuds they have exceptionally personal without damaging any of the party themselves. The party has a fun little fort for when the bad guys come calling. The list goes on and on.