Welcome to Ringworld, an intermediate step between Dyson Spheres and planets. The gravitational force created by a rotation on its axis of 770 miles per second means no need for a roof. Walls 1,000 miles high at each rim will let in the sun and prevent much air from escaping. Larry Niven's novel, Ringworld, is the winner of the 1970 Hugo Award for Best Novel, the 1970 Nebula Award for Best Novel, and the 1972 Ditmars, an Australian award for Best International Science Fiction.

Fleet of Worlds takes a closer look at Human-Puppeteer (Citizen) relations and the events leading up to Niven's first Ringworld novel. Kirsten Quinn-Kovacks is among the best and brightest of her people. She gratefully serves the gentle race that rescued her ancestors from a dying starship, gave them a world, and nurtures them still. If only the Citizens knew where Kirsten's people came from.

Nothing quite prepared telepath Larry Greenberg for mind-to-mind contact with an alien. In the interest of science, Larry tapped the mind of Kzanol - and that was his first mistake. Kzanol was a thrint from a distant galaxy. He had been trapped on Earth in a time-stasis field for two billion years. Now he was on the loose, and Larry knew everything he was thinking. Thrints lived to plunder and enslave lesser planets - and what the planet Kzanol had in mind was Earth!

At first, only a few things are known about the celestial object that astronomers dub Rama. It is huge, weighing more than ten trillion tons. And it is hurtling through the solar system at inconceivable speed. Then a space probe confirms the unthinkable: Rama is no natural object. It is, incredibly, an interstellar spacecraft. Space explorers and planet-bound scientists alike prepare for mankind's first encounter with alien intelligence.

The Mote In God's Eye is their acknowledged masterpiece, an epic novel of mankind's first encounter with alien life that transcends the genre. No lesser an authority than Robert A. Heinlein called it "possibly the finest science fiction novel I have ever read".

There's a reason We Are Legion was named Audible's Best Science Fiction Book of 2016: Its irresistibly irreverent wit! Bob Johansson has just sold his software company for a small fortune and is looking forward to a life of leisure. The first item on his to-do list: Spending his newfound windfall. On an urge to splurge, he signs up to have his head cryogenically preserved in case of death. Then he gets himself killed crossing the street. Waking up 117 years later, Bob discovers his mind has been uploaded into a sentient space probe with the ability to replicate itself.

It is the year 12,020 GE and Emperor Cleon I sits uneasily on the Imperial throne of Trantor. Here in the great multidomed capital of the Galactic Empire, 40 billion people have created a civilization of unimaginable technological and cultural complexity. Yet Cleon knows there are those who would see him fall - those whom he would destroy if only he could read the future.

The gigantic comet had slammed into Earth, forging earthquakes a thousand times too powerful to measure on the Richter scale, tidal waves thousands of feet high. Cities were turned into oceans; oceans turned into steam. It was the beginning of a new Ice Age and the end of civilization. But for the terrified men and women chance had saved, it was also the dawn of a new struggle for survival--a struggle more dangerous and challenging than any they had ever known....

Best-selling science fiction superstars Larry Niven and Jerry Pournelle combine their talents with those of Steven Barnes in an extraordinary adventure of humankind’s first outpost in the farthest reaches of space. Light years from Earth, colonists land on a planet they name Avalon. It seems like a paradise—until native creatures savagely attack. It will take every bit of intelligence, courage, and military-style discipline to survive.

Winner of the Nebula Award for Best Novel, Red Mars is the first book in Kim Stanley Robinson's best-selling trilogy. Red Mars is praised by scientists for its detailed visions of future technology. It is also hailed by authors and critics for its vivid characters and dramatic conflicts.

For centuries, the red planet has enticed the people of Earth. Now an international group of scientists has colonized Mars. Leaving Earth forever, these 100 people have traveled nine months to reach their new home. This is the remarkable story of the world they create - and the hidden power struggles of those who want to control it.