Take the path (lined with imps) past the depleted ore mine to get to the harbour (when it branches, the left path heads up to High Hall, while the right leads down to the harbour. There is no way to take out the anti-dragon shields around either location. You can fly most of the way there, and transform back to human before or above the shields (most of the shields extend higher than you can fly, but you can get above some places near the harbour).
There is a door that is easy to miss into the harbour building, on the same side as the elevator platform, near the fish merchant.