The original volumes, in internal chronological order, are:
- They Shall Have Stars (1956)
- A Life for the Stars (1962)
- Earthman Come Home (collection, 1952)
- The Triumph of Time (1958)
The series is a grand, sweeping epic, based on the development of a form of Applied Phlebotinum called "the Spindizzy drive", which provides cheap anti-gravity, artificial gravity, force-fields, and faster-than-light travel. So cheap and powerful is the Spindizzy that most of the major cities of Earth decide to take off and head for the stars.
This series provides examples of:
- Apocalypse How: Universal/Physical Annihilation: The Triumph of Time ends with the destruction of the entire Universe. However the Multiverse endures, as everyone is given the opportunity to shape a new universe themselves. The main character believes so much in free will that he refuses to give any shape to his own new universe and blows himself up, thus creating a totally random universe.
- Arcology: Cheap and easy anti-gravity and faster-than-light technology leads to most of Earth's major cities converting themselves to arcologies and setting off for the stars.
- Casual Interstellar Travel: This is done with cities and indeed entire planets, when a new law of physics shows that the larger an object is, the easier it is to move at hugely FTL speeds. At one point it is stated that a spacecraft is crossing the solar system at FTL speeds powered by a few ordinary batteries.
- Colony Drop: The rogue city known as Interstellar Master Traders does this with a flying city in Earthman Come Home.
- Inverted When New York City sticks a bunch of Spindizzies on an uninhabited planet, and flies it into the Vegan Orbital Fort.
- Cool Starship: The devices called "Spindizzies" lift up whole cities and send them into space. It's just as cool as it sounds. They can also be used on whole entire planets.
- Domed Hometown: Blish created not only domed cities out of familiar earth cities like Pittsburgh and New York but they travelled through space looking for work.
- Doomed Hometown: The flying cities are forced off Earth by the disaster of world conquest by a totalitarian state. So each of them is a town with a Doomed Hometown.
- Floating Continent: The "spindizzy"—the Applied Phlebotinum that allows for Anti Gravity, Force Fields, Artificial Gravity, and Faster-Than-Light Travel—works better with larger masses. As a result, eventually, entire Terran cities cut themselves free of the planet and soar out to the stars.
- The Great Politics Mess-Up: The series involves the Western democratic government model becoming ever more intolerant, eventually resembling the Soviet model very closely, and then the Soviets winning the war (and absorbing the West) because they were better at being Soviets.
- Hobos: Mayor Amalfi likens the titular cities to the migrants of the United States, saying that most cities are hobos, migrant workers, but some are tramps, basically petty criminals, and a few are the lowest sort: bindlestiffs, migrants who live by robbing other migrants.
- "London, England" Syndrome: Earth's cities, fitted with antigravity generators and spacedrives, roam the Galaxy looking for work. Nevertheless, they still use names like "Chicago, Illinois" or "Scranton, Pennsylvania". This even becomes a plot point when one character spots the error in a city's name and realizes it's actually an alien battlestation.
- Lost Colony: The planet He.
- Moving Buildings: The stories take this to its (il)logical conclusion by having entire cities fitted with antigravity and faster than light propulsion. The idea of flying cities was later used in a British Airways commercial depicting Manhattan in flight.
- New York Is Only Manhattan: The flying city of New York consists only of Manhattan.
- Oppressive States of America: In the first book, America is rapidly becoming a totalitarian state ruled by the hereditary head of the FBI, Francis X. MacHinery.
- Overdrive: The cities of the title can fly at faster-than-light speeds, but they're all equipped with a gadget called "Situation N" which can instantly teleport them away from trouble. Only thing is, it can only ever be used once per city. Why? Because if they used it more than once it would be too convenient for the author, I guess.
- Situation N has the great disadvantage of depositing the affected city in a completely unknown location, a very long way away. As it happens, this becomes a plot point but there us no given reason why the City would not find itself stranded in interstellar space, unable to navigate, seek work or even able to transit anywhere useful within its available supplies. Indeed, there is a specific penalty whereby a City can be broken up to prevent this being attempted, and City Fathers have been known to execute or otherwise depose city managers to prevent this.
- Pandeism: The final section (The Triumph Of Time) has several characters decide to have themselves thrown 'outside' of the universe it's going to temporarily cross "through" another universe; they (most likely) won't survive the process in space suits packed with explosives. The expectation is setting off the explosives would allow each character to become a personalized "big bang", with the resultant baby universes having their physical constants being 'seeded' by the constants contained within each astronaut.
- Planar Shockwave: There is an explosive TDX that only explodes perpendicular to the local gravity field.
- Remember the Alamo: In the series, it's "Remember Thor V!"
- When Things Spin, Science Happens: Implied in the Spindizzy drive. Spindizzies are based on P. M. S. Blackett's work on planetary magnetism, correlating magnetism, gravity, and angular momentum. Some writers (like this one) say that "spin [it] dizzy" is what the device does to the subatomic particles: changing their angular momentum. However, because the device itself is never actually seen or described in canon, its possible that it, itself, spins.
- Worthless Yellow Rocks: Played With. The protagonists carefully save up selenium for use as currency. After they come back to "civilization" some time later, they are told that it's a "fine and useful metal, but you buy it, you don't buy things with it." Ironically, the sellers want a "valuable" metal like... gold.