1st century

The  was a century that greatly interested the Doctor and his companions. The First Doctor, Ian and Barbara made at least three separate trips to the century. (DW: The Romans, PDA: Byzantium!, ST: The Last Days) Meanwhile, the Seventh and Tenth Doctors were both known to be in Pompeii for the eruption of Mount Vesuvius in 79 as was Jack Harkness, apparently more than once. (DW: The Fires of Pompeii; BFA: The Fires of Vulcan, DW: The Doctor Dances). Considerably later in his personal timeline, Harkness was entombed beneath Cardiff for a total of 1,874 years, specifically from 27 to 1901. (TW: Exit Wounds)

Rome vs. Jesus Christ
The first century was dominated by the birth and life of Jesus Christ, the founder of the eponymous Christian religion. The birth took place in a stable next to an inn in Nazareth, (PDA: Byzantium!) because the Doctor had taken the last room in the inn. (DW: Voyage of the Damned)

This event was so monumental that many nations, particularly those of Europe and the Middle East, reoriented their calendars to consider the time before his birth as BC, and the time after his birth as AD, or Anno Domini. (DW: Earthshock) Towards the middle of the century, Christ was crucified, and, according to some, rose again from the dead. This miracle spawned many tales of his godhood, and was ultimately the fact at the core of Christianity. People, mostly former Jews began to believe in Jesus' godhood, and thus the religion began to radiate out from its origins around in Judea, the place of Christ's birth, eventually sweeping out across the Mediterranean this century. (PDA: Byzantium!)

A counterveiling force was that of the Roman Empire. In part because it was polytheistic and had official occultism, (DW: The Fires of Pompeii) the government of Rome tended to view Christians and Jews with suspicion. Under the leadership of Caesars Augustus and Tiberius, Christianity was squelched, often by using Jewish leaders against their members that had converted to Christianity. (PDA: Byzantium!) Even by the time of the later Caesar, Nero, at least some Christians who were Roman citizens chose to keep their religion hidden.

The lure of a good volcano
The Doctor was present in the

Companions lost
During this century, the Alliance tried to put the Eleventh Doctor in the Pandorica, but he escaped. Instead, Amy Pond began a more than 20 century residence of the box, with an Auton duplicate of her fiancé standing watch. It was unclear, however, whether the events of Big Bang Two eventually invalidated this historical fact. (DW: The Big Bang)

In a similar vein, the Ninth Doctor's former companion, Jack Harkness was buried underneath what would become Cardiff. He stayed underground, dying and returning to life, until he was eventually exhumed in the early 20th century. (TW: Exit Wounds)