There's an abandoned subway tunnel system from Westlake (1138 Wilshire Blvd neighborhood) to Downtown L.A.
Old Subway Terminal Building for that line right near MOCA.
https://en.wikipedia.org/wiki/Subway_Terminal_Building
https://www.urbanghostsmedia.com/2014/07/hollywood-subway-downtown-la-abandoned-underground-railway/
Just a block away from the LA Metro’s current Red Line, a luxury apartment building known as Metro 417 occupies a 1925 Renaissance Revival structure originally called the Subway Terminal Building. It was here, several stories below street level, that Hill Street station served 65,000 commuters each day at its peak in the mid-1940s.
And as journalist Alissa Walker discovered during a tour of the building, the abandoned ghost station on the so-called ‘Hollywood Subway’ still exists, a silent time-warp beneath the busy streets of downtown LA.
An arrow on the wall pointed the way to Hill Street station, the original terminus of the Pacific Electric Railway’s Hollywood Subway branch. Other signage, untouched for decades, identified tracks one and two, their rails long since removed.
From here, a ramp descends to the platform. The vast open space, empty since the 1950s, give way to a series of dark, damp tunnels that once catered to busy trains operating between the Westlake neighbourhood and downtown Los Angeles.
Unfortunately, early 2014 spelled bad news for the historic Hollywood Subway. Alissa Walker reported on her blog that “according to Metro 417 the tunnels are now condemned and no longer available for touring of any kind”