Each year on the second Saturday in May, Cincinnati Heritage Programs spends a day giving tours of the city's abandoned subway system to 250 lucky participants. Tickets for the tour go on sale in late January and sell out within 48 hours. It's no secret - people are clambering to get down into the forgotten tunnels which have remained incomplete since 1928.

Cincinnati's subway is  located underneath Central Parkway, with the first station entrance positioned in the median at the intersection of Race Street. The original construction planned for a 13-mile loop that extended from Downtown through Northside to Norwood. Six stations were erected before construction halted; 2.2 miles of tunnels remain today.

So what caused the Cincinnati Subway project to fail? A combination of politics and money. Delays with the project led to increased expenses due to inflation. World War I also caused the prices of construction materials to skyrocket. A change in political leaders ultimately led to the subway's demise, as the new form of government did not want to support any project of the previous administration; it was viewed as an impediment to reform. Sound familiar?

If you missed the Cincinnati Subway Tour this year, check out the next best thing: the PBS documentary "Cincinnati's Abandoned Subway." It includes over 1,500 original construction photographs from the 1920s, interviews with eight local experts, as well as vivid present-day footage of the subway tunnels.