Archaeologists say they've found the oldest Mayan calendar yet - and in what will be a bit of a blow for anyone that's already sold their house and taken to the hills, it runs well past 2012.

The calendar appears on a wall in a building in Xultún, a sprawling city in Guatemala's Petén region. The building appears to be a studio for the local scribe, with walls covered with paintings and hundreds of scrawled numbers - many of which are calculations relating to the Mayan calendar, says the team.

The tiny, millimeter-thick, red and black glyphs are unlike any seen before at other Maya sites, but appear to represent the various Mayan calendrical cycles - the 260-day ceremonial calendar, the 365-day solar calendar, the 584-day cycle of the planet Venus and the 780-day cycle of Mars.

"For the first time we get to see what may be actual records kept by a scribe, whose job was to be official record keeper of a Maya community," says archaeologist William Saturno of Boston University.

"It's like an episode of TV's 'Big Bang Theory,' a geek math problem and they're painting it on the wall. They seem to be using it like a blackboard."

And, despite popular belief, there's no sign that the Mayan's believed the world would end in 2012.

"It's like the odometer of a car, with the Maya calendar rolling over from the 120,000s to 130,000," says Anthony Aveni, professor of astronomy and anthropology at Colgate University. "The car gets a step closer to the junkyard as the numbers turn over; the Maya just start over."

The numbers appear on the west wall of the building, and appear to include dates some 7,000 years on the future. One appears to record the date they were painted - 813 AD, just as the Mayan world started to collapse.

"The ancient Maya predicted the world would continue, that 7,000 years from now, things would be exactly like this," says Saturno. "We keep looking for endings. The Maya were looking for a guarantee that nothing would change. It's an entirely different mindset."