The TTC is the "Ticket, Transportation Center." It's the connection of the monorail lines (MK, resort, EPCOT) and the ferry boats to MK from the MK parking lots. When there was only 1 park (like my first visit), this was where the magic started. You drove to WDW, parked in "the" parking lot and decided if you wanted to take the ferry or the monorail to MK. Part of Walt's magic to "take you to a different world". Both went across the lake to "The Magic Kingdom".
The buses are ok and will get you from point A to B, but the boats are still part of the magic for me.
j