This is hopefully a regular effort to both delight and confuse my friends.
Exhibit A: A brilliant map from the 1860's that charts the progress of Napoleon's diminishing forces as he attacked Moscow and was forced to return home; it also tracks the temperature at different points during the campaign.
Exhibit B: Swedish dance bands of a bygone day. Suddenly Abba looks incredibly tasteful. Warning! Not for the faint of heart, though SFW.