Which country in Europe has the oldest continous monarchy?

England has the oldest continues monarchy by a very long way it started in 400ad until the present queen Elizabeth ,Elizabeth by blood is related to all of them whether the houses have changed or not . No monarchy has survived that length of time in the world let alone Europe. The one break was Cromwell but Charles the second was returned to the throne and as he was the son of Charles the first the line was unbroken .