15 Best Mysterious Alien Megastructure Books

The Well World is a planet-sized computer that acts both as the controller of and the gateway to 1560 worlds created by an ancient and extinct alien race.

Answering a distress call, starship captain Nathan Brazil and his passengers are suddenly transported to the Well World by a hidden gate.

There, Nathan Brazil must stop mysterious forces from taking control of the Well World, and through the Well World, the universe. But to do so, he must deal with bizarre transformations, which have changed people into centaurs, mermaids, and giant insects. In this strange land, inhabited by these strange, transformed creatures, he doesn’t know who are his friends, and who are his enemies. And what of his own memories, which seem to have been deeply suppressed?

In the future, there is a city grown so chaotically massive that its inhabitants no longer recall what “land” is. Within this megastructure the silent, stoic Kyrii is on a mission to find the Net Terminal Gene—a genetic mutation that once allowed humans to access the cybernetic NetSphere. Kyrii fends off waves of attacks from fellow humans, cyborgs, and silicon-based lifeforms. Along the way, he encounters a highly-skilled scientist whose body has deteriorated from a lengthy imprisonment but who promises to help Kyrii find the Net Terminal Gene, once she settles a score for herself…

At the time of writing this list (August 2018), Blame! is also an anime movie on Netflix.

The Ship has traveled the universe for longer than any of the near-immortal crew can recall, its true purpose and origins unknown. It is larger than many planets, housing thousands of alien races and just as many secrets. Now one of those secrets has been discovered: at the center of the Ship is a planet: Marrow. But when a team of the Ship’s best and brightest are sent down to investigate, will they return with the origins of the Ship—or will they bring doom to everyone on board?

“Reed’s ambitious, detailed premise and thoughtful manipulations of space and time make for an enjoyable reflection on the size and shape of the universe relative to its human inhabitants.”
— Publishers Weekly

This is one of my favorite SF books.

One night, a boy watches the stars flare and go out. The sun is now a featureless disk—a heat source, rather than an astronomical object. The moon is gone, but tides remain.

It’s a rare author that can start with such an intriguing premise and carry it through, while exceeding expectations. I recommend this book strongly, as well as the other two in the series, Axis and Vortex.

It has been nearly a decade since the completion of Gene Wolfe’s four-volume epic The Book of the New Sun, a wildly popular books series, but unloved by me.

Nightside The Long Sun is the first book in the The Book of the Long Sun series, set on a world called the Whorl, which exists inside a giant starship sent from Urth to colonize a distant planet. The Whorl’s origins are shrouded in legend, and it is ruled by strange gods who appear infrequently to their worshippers on large screens, and peopled by a human race changed by eons of time.

While struggling to satisfy the gods aboard The Whorl, Patera Silk unwittingly discovers a new god. This does not go over well in the Whorl.

Gateway is a space station built into a hollow asteroid constructed by a long-vanished alien race. Inside the station are nearly a thousand small, abandoned spaceships, but nobody knows where a particular setting will take the ship or how long the trip will last. Most settings lead to useless or lethal places. A few, however, result in the discovery of alien artifacts and habitable planets, making the passengers extremely wealthy. Very high risk, very high reward.

But if you live on an impoverished and overcrowded Earth like Robinette Stetley Broadhead, even ridiculously long bets start to look good.

Warning: This is book 3 of 3 in the Coyote Universe series. You may want to check out Spindrift and Galaxy Blues first.

Hex is a habitat the size of an entire solar system that could be a utopia—or nothing but a cosmic mirage…

The danui, a reclusive arachnid species, have avoided contact with the Coyote Federation—until now. Initiating trade negotiations, they offer only information: the coordinates for an unoccupied world suitable for human life—a massive sphere composed of billions of hexagons.

But when the Federation’s recon mission goes terribly wrong, the humans realize how little they know about their new partners…

“Steele has been progressively widening the screen throughout this series, and with Hex he bumps the aspect ratio up to IMAX level and sits us in a front-row seat.”
— Locus

Graduate student Tom Rice is thrilled to embark on his first deep-space archeological expedition. He is part of a team from Earth, venturing out in search of artifacts from a civilization that ruled the universe many millennia ago. Called the High Ones, the members of this long-gone society left tantalizing clues about their history and culture scattered throughout space. One such clue, a “message cube” containing footage of the ancient ones, is more interesting than all of the others combined. It seems to indicate that the High Ones aren’t extinct after all—and just like that, Tom Rice’s archeological mission has become an intergalactic manhunt, one filled with ever-increasing danger that will send the explorers hurtling headlong into the greatest adventure—and peril—of their lives.

“No matter if Silverberg is dealing with material that is practically straight fiction, or going way into the future… his is the hand of a master of his craft and imagination.”
— Los Angeles Times

Nominated for the Hugo, Nebula, and Locus awards. This book’s sitting on my shelf right now.

When Cirrocco Jones, captain of the spaceship Ringmaster, and his crew are captured by Gaea, a planet-sized creature that orbits around Saturn, they find themselves inside a bizarre world inhabited by centaurs, harpies, and constantly shifting environments.

A 300 kilometer-long stone flashes out of nothingness and into Earth’s orbit.

The Stone was from space—but perhaps not our space; it came from the future—but perhaps not our future. Within the hollowed asteroid were the remains of a vanished civilization. An English, Russian, and Chinese-speaking-civilization. Seven vast chambers contained forests, lakes, rivers, hanging cities, and museums describing both the catastrophic war that was about to occur and the long winter that would follow. But while scientists and politicians bickered about how to use the information to stop the Death, the Stone yielded a secret that made even Earth’s survival pale into insignificance.

“Bear’s creativity provides a richness to an intricate, complex plot.”
— School Library Journal

Ringworld is considered a science fiction classic, and it won the Hugo, Nebula, and Locus awards while spawning three sequels and four prequels.

An expedition’s goal is to explore a ringworld: an artificial ring about one million miles wide and approximately the diameter of Earth’s orbit (which makes it about 600 million miles in circumference), encircling a sun-like star. It rotates, providing artificial gravity that is 99.2% as strong as Earth’s gravity through the action of centrifugal force. The ringworld has a habitable, flat inner surface equivalent in area to approximately three million Earth-sized planets.

The explorers crash on the ringworld and make some surprising discoveries.

This highly influential 1937 book is more a psychedelic trip through a cosmos filled with weird, alien life than a conventional actioneer. There’s no real plot.

The narrator, a contemporary Earthman, joins a community of explorers who travel to the farthest reaches of the universe, seeking traces of intelligence. Along the way, they encounter nautiloid water beings, races of hyperspiders and hyperfish, composite group intelligences, plantlike creatures, and other strange life forms. Their voyage unfolds against a backdrop of life-and-death struggles on a cosmic scale.

Constructed for an unknown purpose by a long-dead race, Shellworlds are ancient artificial planets consisting of nested concentric spheres internally lit by tiny thermonuclear “stars.” The spheres are inhabited by various primitive races, along with progressively more advanced species.

The book follows the experiences of three siblings of the royal household of the Sarl, a feudal, pre-industrial humanoid race living on the eighth level of the Shellworld. In the midst of a war, their father is murdered, and they must battle betrayal and alien secrets to regain control of their kingdom.

“Beautifully written and filled with memorable characters and startling technology, this tale of intricate politics and interstellar warfare ably demonstrates that Banks is still at the height of his powers.”
— Publishers Weekly (starred review)

One of Saturn’s moons suddenly departs from its orbit and shoots off into deep space. The only nearby ship chases the errant moon and watches as huge chunks of ice fall off its surface to reveal a gigantic machine underneath.

Not everyone on the ship wants to keep chasing this object. The object seems to have some ideas about that, too.

Pushing Ice is a great book, and I lost some sleep because I couldn’t put it down. Even though we follow the same characters throughout the book, so much happens that it has the feel of a big, sprawling, multi-generational epic.

The science is hard, the humans flawed, and the surprises keep coming.

“Spectacular… [Reynolds] has a genius for big-concept SF and fans of Arthur C. Clarke’s Rendezvous with Rama and Larry Niven’s Ringworld will love this novel.”
— Publishers Weekly

An uncontested sci-fi classic, Rendezvous with Rama is also one of Clarke’s best novels, winning the Campbell, Hugo, Jupiter, and Nebula Awards.

A huge, mysterious, cylindrical object appears in space, swooping in toward the sun. The citizens of the solar system send a ship to investigate before the enigmatic craft, called Rama, disappears. The astronauts given the task of exploring the hollow cylindrical ship are able to decipher some, but definitely not all, of the extraterrestrial vehicle’s puzzles. From the ubiquitous trilateral symmetry of its structures to its cylindrical sea and machine-island, Rama’s secrets are strange evidence of an advanced civilization. But who, and where, are the Ramans, and what do they want with humans? Perhaps the answer lies with the busily working biots, or the sealed-off buildings, or the inaccessible “southern” half of the enormous cylinder. Rama’s unsolved mysteries are tantalizing indeed. Rendezvous with Rama is fast-moving, fascinating, and a must-read for science fiction fans.