It appears to be a wooden crate and has several entrances and several wooden columns as well with some stairs. There is a roundabout in front of the building with a flag in the center of the said roundabout.
In the front of the building is the judge's stand and the stand to the left of said judge's stand. To the back of the building is the entrance of the main room. There is a jury stand to the left of the building and benches towards the back of the room.
After Mr. Krabs gives SpongeBob a mission to find out who stole the Krabby Patty secret formula, and after Mr. Krabs accusing him of stealing the formula, SpongeBob sees the formula in Mr. Krabs' hand. He reveals that the whole situation was to just avoid paying $1.99 in delivery.
He then goes to the court house, and gets punished by having to give away Krabby Patties for free for a whole day.