Yes, Jason, I have some of the signs that once hung inside that "subway". It was/is a wide (maybe 20') tunnel under all of the tracks out to the last gate. between every two tracks, there was a ramp or stairs that brought one up to platform level, often between two trains! We had 29 boarding tracks and about 15 platforms. The platforms were labeled as "gate 1 - ?" Then the tracks labeled 1 - 29. It was easy to find your train, for example gate 8 track 16. The subway had pumps (hidden) that kept the creek out of it. After the depot closed, it flooded with really nasty water and became a toxic waste dump for the homeless. I seem to remember it being done in tile with concrete floors. My understanding is that when they built the new Convention Center on the site (huge mistake) they pushed construction debris into the subway and covered it over. Bottom line, since it was built to hold up the weight of steam locomotives, I don't think it was completely caved in, in fact, it is probably still there, waiting for TC to restore it.
Ocklawaha