Ruined Portals are broken Nether portals found in both the Overworld and the Nether, making them the only structure to generate in two dimensions. They appear in nearly all biomes (except deep dark), often surrounded by netherrack, lava, and stone. Portals can generate above ground, underground, or underwater, with terrain-based variations like mossy blocks or vines in jungles.

Each portal consists of damaged obsidian frames, sometimes mixed with crying obsidian (which cannot activate a portal), and is surrounded by debris such as stone bricks, iron bars, and blackstone in the Nether. A loot chest usually generates nearby, containing items like obsidian, gold tools/armor, gold nuggets, flint and steel, and rare items like enchanted golden apples or lodestones.

There are 13 portal variants: 10 small and 3 giant. Giant Ruined Portals have a 5% chance to spawn and are more elaborate, often with more gold blocks and lava. Some Ruined Portals lie flat or appear incomplete, suggesting age or destruction. Most contain enough obsidian to complete a working Nether portal if players remove any crying obsidian.

Ruined Portals offer a reliable early-game source of Nether materials and gold loot.