The above drawing is of the infamous Chicago Wigwam--a temporary building built of canvas and wood for the 1860 Republican Convention.
This structure was the deal breaker for getting the convo to Chicago in the first place. Each city--New York, Philadelphia, some smaller towns--put forth their bid for the spectacle, but Lyman Trumball and Gustav Koerner won out.
Seems Chicago was the right place at the right time, and the Illinois team promised huge discounts on train travel (hmmmm--did someone know a tall, gangly railroad lawyer?) as well as a building to be designed and built--at city expense!!--to provide a place for the Republican delegates.
I present . . . THE WIGWAM!