The last of the three small unused subway tunnels in Cincinnati was sealed off this month:
This tunnel was built in 1925. It's about 700 feet long. The north portal was sealed sometime around 1965. The south portal doors were vandalized at some point in the 1980s and never repaired, meaning people were free to visit this short tunnel any time they wanted.
Two similar short tunnels in Norwood are sealed off. One was sealed around 1975 and the other in 2005.
The much longer downtown tunnel, which measures about two miles and has three underground stations, remains intact. It has steel doors that can be opened by city staff for regular inspections.