Rome

Rome was a city in Italy. It played an important role in Earth history, most notably as the center of the Roman Empire, a large Empire in early Human history.

Around the 5th century BC, the Cult of Demnos flourished in Italy. (DW: The Masque of Mandragora)

It was the new home of the Caecilius family after the destruction of Pompeii in 79 CE. (DW: The Fires of Pompeii)

An Alternative version of 41 BC Rome was created by the Rani, but with more advanced technology. (MA: State of Change)

A group of Roman soldiers was kidnapped by the War Lords for use in their war games (DW: The War Games)

In 1923 a British archaeological survey of Rome by professor Livesy-Smythe turned up a scroll by Caecilius telling of the true faith of Pompeii, first alerting Torchwood to the existence of the Pyroviles. (Captain Jack's Monster Files)

In the year 12005, the New Roman Empire flourished. (DW: The End of the World)
 * no further details are known, but it was presumably inspired by the original Roman Empire, and thus most likely had it's capital in Rome.