I’m a bit tired so the post is short; we saw a very nice collier site. These remains are common in the Swedish woodlands. Most often one find the remains of the process consisting of a charcoal bottom; it’s often round, ca 5-10 m in diam. and 0,2-0,5 m high and the ruins of a small hut.
This hut, and the furnace in particular, is well preserved.