New New York

New New York was one of the main cities of New Earth and a recreation of New York City on Earth. It had a Duke, a police force, and a hospital run by the Sisters of Plenitude though this was across the river from the city.

The city had a population of at least ten million. The Tenth Doctor jovially noted that it should have been called "New New New New New New New New New New New New New New New New York", because it was the fifteenth New York built. (TV: Gridlock)

History
After Earth was destroyed by Sol expanding, a revival movement began, and the nostalgic humans moved to New Earth. The Sisters of Plenitude had been growing cloned humans infected with every known disease as a way of quickly treating diseases. Lady Cassandra, taking over Rose Tyler's body, freed a floor of the clones, who in turn released all of the other ones and they attacked New New York Hospital. The Tenth Doctor and Cassandra cured the clones, breaking the quarantine, the Sisters were arrested and Cassandra was released from Rose's body. (TV: New Earth)

However, life then became harsh for the population. Pharmacists sold mood drugs, setting up shops in the Undercity. When a new mood drug called Bliss was created, the Upper City became addicted to it. A virus then mutated in the chemical and became airborne, killing everything in seven minutes flat. To protect the rest of the population, the lower city and the Motorway were sealed off and New Earth was placed in automatic quarantine lasting for one hundred years. Sealed off from the Undercity and the M87 Galaxy, the virus had nothing to feed on, to which it starved to death. The Motorway, meanwhile, had at some point become home to Macra, who fed off the gases emitted by the vehicles therein.

Eventually, in the year 5,000,000,053, the Tenth Doctor visited the city again, (this time with Martha Jones) landing in Pharmacytown. He encountered the pharmacists, still selling mood drugs. With the help of the Face of Boe, he saved the people on the motorway by unsealing the exits and opening the roof section, allowing those trapped to escape and recolonise the city. Using all his life energy to open the motorway roof, the Face of Boe died. (TV: Gridlock)

In that same year, Rose-the-Cat landed the TARDIS in New New York, where she caught a fish. (COMIC: A Rose by Any Other Name)

Behind the scenes
Efrog Newydd Newydd Nuova New York
 * The name has been used several times before in works of fiction.