6. The Dupont Underground, Washington, D.C.
Location: Washington, D.C., under Dupont Circle.
1862 is the year.
Cost: The anticipated cost of renovations in 2015 was $750,000.
One of the busiest neighborhoods in Washington, DC, is Dupont Circle. There are several tunnels and an abandoned trolley station beneath these busy streets. Dupont Circle is now utilized as an art space, even though it was not intended to be used for that purpose.

Washington, D.C.’s Dupont Underground: @atlasobscura/Pinterest
For a hundred years, Washingtonians were transported around by the Dupont Underground. The trolleys were once carriages pulled by horses. Up until the 1960s, when the Metro line entered the planning stage, the Underground was in service. The Dupont Underground has had brief stints as a food court and a nuclear fallout shelter, both of which ended tragically. It is now a self-created artwork featuring intriguing graffiti.
