I know that this is probably quite useless for the rest of you, but we
do have a wonderful collection of materials about Stockholm called Stockholmskällan
(Source of Stockholm). It's full of old photos, maps and documents, as, for instance, this map from 1869
that shows the official toboggan-riding hills/streets in Stockholm (you
can click on the map to make it bigger). I had no idea that there were
streets officially designated for this. Could be a good piece of
information for a novelist...