[RightWhale]

That's right. Over here in Alaska magnetic north is about 30 degrees northeast. I don't know of any ancient civil works around here that are aligned with magnetic north, but sometimes someone builds his house that way thinking it is true north.

[Carry_Okie]

If the symmetry of the map above is correct, the declination would be about 14-15°, not 20°. That's what it is in California.