Minecraft wiki entry for Building_a_metropolis, associated text: Spooky: This type of city is possible to build anywhere, but swamps, due to the murky water and dark foliage, are one of the best settings for a city like this. Getting rid of all peaceful mobs can help to make the atmosphere scarier. You should use /gamerule doDaylightCycle false, and then set the time to night, it looks even better if it happens to be a full moon or new moon. For extra effect, you can also use the /weather thunder on a repeating command block to create a permanent thunderstorm. Use dark and dilapidated-looking materials for buildings. It is even better if you use stairs and slabs to make it all look like broken masonry. There could be several graveyards (with spawners under tombstones if you want), flooded houses, trampled farms, or anything that would make the place looks really creepy. You can have dark caves right under the city, which produce ambience noises, or use command blocks to produce them. Add shrines and dungeons and maybe right in the middle of the city, you could add Herobrine's castle or a statue of him. You could inhabit it with hostile mobs but a completely abandoned city can have a scary atmosphere as well.