I don’t know what channel this show was on, because I had the DVDs as a child; but I know that I watched it around 2008–2009, so it would have come out a little before then (maybe 2006?).
The plot, as much of it as I remember, is as follows: four teens get sent back in time and are jumping from important location in history to important location in history. One of the episode plot lines deals with Paul Revere, and one of the characters has to hang the lanterns on the Old North Church steeple. I can’t remember if this happens in the same episode, but there's also a plot line where the bad guys (who have been chasing the teens through time) tried to poison Ben Franklin, so that he couldn’t sign the Declaration of Independence. (That was kind of the bad guys' thing—they wanted to stop important events in history from happening.)
In another episode, the teens are sent back to ancient Rome and are sent into this Colosseum-like arena. (I don’t think it was the Colosseum because they were in Pompeii but creative license and all.) I remember in this episode they had to escape the arena and get away from Pompeii before it was destroyed. There was also this Roman citizen named Guy. The group saves him; he ends up being important; and it turns out that the bad guys were trying to kill him so he wouldn't document the eruption of Mount Vesuvius.
If it helps, it was in English. I don’t remember what animation style it was in, however.