One of the ways to make your game world more realistic is to give it signs of a history and secrets. Think of The Fellowship of the Ring movie when thy paddle down the river and you see the giant statues of long distant kings. Another fairly well-known example is the DragonLance novels which take place after several other ages; the world has a blood sea caused by events in a prior age.

The list below notes many wonders or mysteries of our real world (and a few from other worlds) and gives several ideas of possible reasons each exists and/or purposes and uses in a fantasy or science fantasy game. You can roll randomly or pick what best fits your game world. And of course these are just skeletons of ideas… you’ll want to flesh them out or use them to inspire a completely new idea!

Hanging Gardens (of Babylon) Gardens contain a special magic source enhancing some types of magic. Contain rare plants useful for unusual spells or healing. Great temple to a nature god. Symbol of an alliance between a nation-state and a nature-loving race such as Treants, Unicorn, etc. A single lonely mountain. (Stone Mountain, Ayers Rock) Giant egg (surrounded by a stony shell) of an alien or huge monster. Powerful monster encased in stone. Alien spacecraft. Earth Elemental resting for ages. Giant Outlines of Animals (Nazca Lines) Mark locations of areas under a creature’s protection. Planned locations of monuments. Druidic worship areas. Spaceship landing sites or location markers. 100s of Stone Warriors (Terracotta Army) Army petrified by a beast (basilisk, medusa, etc.) Army placed in stasis to defend the area later. Monument to warriors in a great battle. Army for a dead emperor’s afterlife. Pyramids (Egyptian) It is or contains a spaceship. It is a portal to other planes. Giant museum. It is a library. (Make it foreign with non-traditional books–maybe cubes or some other shaped object.) Pyramids (Central American) Worship site containing a sacred location or object. Tomb to a great emperor. Marks a celestial event which happens every 1000 years… including next year! Contains ancient home of an evil cult. Sunken city/island (Atlantis) City was cast underwater by an angry god. An earthquake dragged the city underwater but a sea-god transformed the population into merfolk or otherwise allows them to breathe water. The city was always underwater but long ago stopped interacting with the surface. City used great magics to create air-domes and magically moved underwater to avoid a great foe. Field/beach of statues (Easter Island) Automaton protectors awaiting activation. A petrified army. Sea creatures turned to stone when out of water too long. A pair of giants’ chess game. Standing Stones (Stonehenge) Druidic temple. Marks the grave of a great warrior or magician. Marks a source of enhanced magical abilities. Tracks celestial event(s). Geyser (Old Faithful) Water spray is the source of magical powers. Spray caused by monsters in the underground sea. Hot water used for “modern” amenities by local town. Not just water spits out of the geyser… Obelisk (Washington Monument) Interplanetary signal by alien monitors. Relays messages between towers of Wizardry. Outside has puzzle by alien race to test the inhabitants. Marks a truce between two all-but-forgotten empires. Great Wall (Great Wall of China) Long ago, served as protection against barbarians. Is an elevated road. Towers contain bonfires ready-to-go to act as a signal system. Inside is a horde of weapons and supplies for an army. Great Waterfall (Victoria Falls, Niagara Falls, etc.) Caves behind lead to an inner world of the planet. Home to the planet’s oldest Water Elemental. Waterfall has magical curative properties, varying based on time of day, celestial events, etc. Deep water has a massive graveyard as many old creatures choose to die there. Colorful, Dynamic Reef (Australia’s Great Barrier Reef) Curated by druids. Home of a tribe of sea unicorns. High-magic item/source is nearby and leaks magical energy that makes the reef healthier, more amazing. 1000 years ago a battle of 10,000 ships was fought. The sunken hulls gave the reef its start. Meteor Crater Impact from a god’s fall. Result of a great magical accident. Alien ship’s landing/launch site. Meteor of unusual material. Effigy – Earth Mounds (Serpent Mound) Creature hibernating just under the surface. Caused as caves were dug under the surface, may be used for burial purposes. Bulette tracks. Representation of constellations above. Mountain City (Mount Olympus) City of the gods. Inter-dimensional meeting place. Purgatory. Home of an advanced civilization monitoring the rest of world. Giant Statue (Colossus of Rhodes) Serves as a lighthouse. Magical protector of a port. Imprisoned monster turned to stone. Military harbor lookout. Colosseum Serves as a source of power to a death god. Under the arena floor is an amazing zoo/prison of all types of creatures. 2x the size of any similar structure. Used for vast religious ceremonies as well as gladiator combat and other entertainment. Grand Canyon Caused by the material that formed the moon being ripped out of the planet. (Is there a hollow world inside?) Path to the center of the planet. Path to the underworld. Caves below or on the sides are home of an ancient cult. (Very hard to reach.) Great Bridge Magical bridge that spans a very long distance. Bridge doesn’t span a river/bay, it actually teleports on each side. Bridge can transform to block water traffic for defensive purposes. (Lowers to surface level so ships can’t pass.) Bridge leads not to the other side, but to another plane. Giant Continuous Storm (Jupiter’s Red Spot) Storm that rages across the planet, never-ending. Legends say it is caused by two gods fighting eachother. It is the result of a god’s curse as he died. Formed by the accidental destruction of a tower of sorcery. Rings Around Planet (Saturn & other planets) Asteroids formed by the destruction of a moon. Magic field that serves to protect the planet from interplanetary/dimensional attack. Destroyed home of the gods. Where did they go? Are they dead? Rings are a device that allows faster than light transport from that world. Vanished City (Pompeii) Destroyed in a nearby volcanic eruption. Coastal city wiped away by a tsunami. Destroyed by an angry god’s vengence. Transported to another place/plane by a magic. Perhaps it was an experiment gone awry? Giant Gemstone (Hope Diamond) Heart of a god. Prophecy says if the gemstone is broken the world will go dark until restored. Traps the soul of a demi-god/demon. Source of great magical power.