Best things to put in/on a Keep

[Poil]

-Spikes with skulls.
-Gargoyles.
-A bound devil or demon. Just because you can.
-Garbage and waste disposal is a short chute ending in a disintegrate trap. Climbing up the fake ones from the outside merely has the intruder being gated to the abyss.
-Trapdoor under the floor in front of the "throne" for annoying guests. Teleportation or gate traps are also acceptable.
-Kobold servants.
-Stable for various kind of rideable animals.
-A tall and creaking tower.
-Haunted mausoleum with matching catacombs.
-Half dragon chimpanzees.
-Pleasant herb garden.

I could go on forever.