Ruins are my favorite part of any story. It fascinates me to learn about the ancient civilizations that lived long before us. Ruins are great for providing world building information to your players while simultaneously giving them an atmospheric experience they are not bound to forget.

Ruins can easily be misused by inexperienced or unaware DMs. For example, take the following situation. Your party is traveling in a forest in search of some magical artifact. You come across a clearing containing ruins. It consists of cracked stone walls covered in moss. You fight some undead enemy that was one of the former inhabitants of this generic castle. You get the artifact and leave. Overall, the players didn't learn anything about the world they are supposed to be immersed in and leave with a rather fulfilling experience.

Ruins can be more than a setting. When designing a ruins encounter, make it more than having terrain that might collapse on you. Add purpose to its being there. Ask the five main questions that were beaten into you in elementary school English. Who, What, When, Where, Why, and (In a loose sense) How.

Let's start with Who. Who built this structure? This doesn't matter too much in the long run.

D12 The structure was built by

1. Humans
2. Giants
3. Elves
4. Halflings
5. Gnomes
6. Fey creatures
7. Orcs
8. Gnolls
9. Trolls
10. Dwarves
11. Tieflings
12. Drow

Next we'll move on to What. What does the structure look like? What is it made of? What is its state of decay? Does it have any unique features?

D6 the structure is made of

1. Wood
2. Stone
3. Metal
4. Sandstone
5. Clay
6. Marble

Next is when. When was it built? When was it destroyed? This does not determine much and can mostly be placed either at a specific date (200 years ago) or near a temporal landmark (during this war. )

Then we come to Where. This is most likely to conflict with the others or with your own campaign, so this will almost always have to be changed if you want to create your ruins with a dice roll. Where is your structure located?

D12 Your structure is located

1. In a forest
2. Inside a mountain
3. On top of a mountain
4. At the bottom of a lake
5. In the air
6. In a dry desert
7. In the tundra
8. On a remote island
9. Beside a river
10. Down an unused road
11. In a charred landscape
12. Deep under the ground

At this point, we have a fully functional setting. However, it lacks the depth of a fully fleshed out story location. This is when we consider what it may have been used for. Why was this structure built?

D20 The structure was used as

1. A defensible location
2. An outpost
3. The main city for a race or faction
4. A hospital
5. A storage facility
6. Lodgings for travelers
7. A library
8. A high security prison
9. A privately owned house
10. A landmark for navigation
11. A lighthouse
12. A theater
13. A border patrol station
14. A Wizard's home
15. A factory
16. A lookout tower
17. A trading post
18. A scientific research facility
19. A mining base
20. A tavern

Finally is How. How was the structure destroyed? How did it get to its current state?

D6 The structure was destroyed

1. In battle
2. Naturally through abandonment
3. In a fire
4. In an earthquake, landslide, avalanche, or storm
5. Through its own poor construction
6. By terrorists or vandals

By now, you have an excellent setting for your ruins with some interesting history to it. However, the history and world building will never get to your players unless you have some way to expose it to them. Try to avoid cliche methods such as a comprehensive history being written in a book. If the structure is in ruins, a book is not likely to survive. Try having scraps of your civilizations history written on cuneiform tablets. If your ruins are in an underground or mountainous area, you can have your PCs attempt to decipher cave paintings. If the structure was ruined in a battle, have a player character relive the battle in a dream after he or she visits the ruins of the structure. You could even leave snippets about it in songs that random tavern bards sing.

Remember our boring ruins encounter from before? Let's see what we can do with our added information. I rolled some dice to get a ruins. It was human built. It was made of wood. It was located beside a river. It was used as a factory. It was destroyed in a fire. We can now sculpt that rudimentary outline into a more refined view.

Let's say that it was a textile factory that used a water wheel to power its machinery. It was destroyed, one winter when the fire got too close to some of the cloth and it started a fire. After the fire burnt the mill and nearby house down and a year passed, all that remained was half of the water wheel, damaged by rot from falling into the river, and some charred hardwood floor. Instead of fighting a generic bland enemy, the party notices a person in a white cloak near the ruins. When asked, the person talks about how it used to be the family business before the fire. She was away from home when the fire happened, and has only recently returned. She then gives the party a jewel necklace belonging to her younger sister who had perished in the fire, claiming that the memories were too much for her to keep the necklace. As it turns out, this is the artifact that they were looking for.

What went from a setting just to change things up a little and provide terrain to fight around has now become a miniature story of its own!