The Underground was a massive subway project started in 1900 as carriage and early automobile traffic became too dense for the narrow city streets. Tunnels were built throughout most of the island, but difficulties arose as the tunnels reached the coasts. The first major issue came in late 1901 when builders accidentally discovered the buried remains of Port Salem. The team began clearing out what used to be the streets of the original district, but was ordered to cease, due to lack of resources and the dangerous state of the buried area.
In 1903, while laying track in what was to be the final segment of subway, a tunnel wall collapsed. The plans had been slightly off, placing the tunnel too close to the coast, causing the force of construction to disrupt the too-thin wall. When the tunnel collapsed, nearly the whole subway system was flooded. At this point, the city deemed the project far too expensive to either repair or properly fill in, thus entrances were sealed and the subway was abandoned.
Sections of the Underground were properly sealed and pumped of water and have been since repurposed. Some businesses have converted sections underneath their building into functional basements or storage space. The most notable use is the large area beneath Lockley University, which houses the primary city generator and energy processor. The few stations that were constructed have also been largely repurposed, with their access to the subway tunnels largely sealed off.