This is about the place. You might be looking for the episode.
The City Of Thieves is located in an arid region in the Land of Ooo and is within a giant turtle shell. The place is filled with thieves, and the entire population of the city probably are thieves. A notable citizen of this city is Penny. The city looks extremely crowded, due to the fact almost all the buildings are smooshed up together. It made its first appearance in the episode "City of Thieves," where Finn and Jake saw it in the arid region. The Hag popped out of a tree, and then told them that those who enter the city will become a thief. Finn and Jake meet Penny and enter the city. At first, it seemed like a run down town, but out of nowhere, people started stealing each others valuables. Finn had stated that he would purify the city, but when everyone began to steal from each other, it was too much for him. There is a store located in the city called Baskets & Boots. Jake stole a pair of red boots, so he lost his chance to enter the tower. It is possible that the city is or formally had a monarchy, due to the fact that there is a King of Thieves, but he has been dead for some time, due to him being bones at the time of the episode.
The buildings here are very crowded. They all have a brown color and a dark brown roof. In the heart of the city lies the King of Thieves' Castle. It is very dark and has a lot of tents and houses.
- Penny said that everything that is stolen from little girls ends up in the King of Thieves' Castle. But technically, it would be impossible, because no thief can get inside the castle to drop it off.
- Even though the Hag said to F&J that everyone who enters the city comes out a thief, she herself entered the city, but still stayed 'pure'.