There can be much debate on whether a site was part of the Underground Railroad. Hudson Valley has its share of sites, ...

Researchers may have found the hidden tunnels beneath a castle in Milan that Leonardo da Vinci sketched in 1495.

The Mount Washington Transit Tunnel will close for eight months to allow crews to perform infrastructure upgrades. The ...

Today, L.A. Metro’s subway tunnels connect some of the city’s most densely populated neighborhoods. There are many other ...