Chattrapati Shivaji Terminus can be reached by sub-urban trains on the Central and Harbour lines. If you are coming on the Western line, then change over at Dadar and reach CST. Buses are also available and you will need to look out for termination point being CST which will be displayed in the front of the Bus.
Auto rickshaws are not allowed in this part of Mumbai, however you can take a black & yellow taxi or OLa or Uber from any part of Mumbai.
The tour commences at the entrance to the sub-urban train ticket counter of Chattrapati Shivaji Terminus. Look for a sign saying “Suburban Booking Office”, written in white on a blue board.