Cincinnati has a subway. Or, rather, the abortive beginnings of one. The digging began in 1920, when streetcars couldn’t keep up with the city’s growing population. But cost overruns and the advent of the automobile gradually turned it into a white elephant. In all, seven miles were prepared, but no cars were ever ordered.

In the years since 1925, when construction stopped, the empty tunnel has been proposed for use as an air-raid shelter, a storage area, a mall, a film set, a wind tunnel, and a wine cellar, but none of these received approval. Instead the entrances have been sealed with concrete, and it remains simply the nation’s largest abandoned subway tunnel.

If enough time passes, perhaps it will be forgotten entirely. Intriguingly, this has happened before.