70

According to the Sixth Doctor, 70 A.D. was the year the Romans began construction of the Colosseum. (PROSE: State of Change)
In the early 21st century, archaeologists at Crediton Vale found a Roman mosaic that the Tenth Doctor dated to this year. On the mosaic was a scene of two people, grapes and a Dalek. This suggests that there were Daleks on Earth in the 1st century AD. When the Doctor arrived at Crediton Vale in 2007 he also identified a turning spike and a pizza slice which would have been use in this year. (PROSE: I Am a Dalek)