That's not a matter of fact, that's a matter of semantics. Checking up on your fact, I find that the Althingi was founded in 930 but suspended in 1789 and Iceland was ruled by Denmark until 1918, so that doesn't sound very continuous.

England has had a (Cromwell aside) unbroken series of monarchs since 1066, does that count?

Still, the US should get some kind of old-government distinction since it's had absolutely uninterrupted constitutional democracy on all levels since Washington's time. (At least in the states that didn't secede.)