I suspect it is because they don't actually know the date of those houses, but just know that they are old. 1005 is strange for Amsterdam, as Amsterdam first r

I suspect it is because they don't actually know the date of those houses, but just know that they are old. 1005 is strange for Amsterdam, as Amsterdam first really became a city in the 1300s. Still, maybe it is just the tool's 'first date' or something.