Here&rsquos your return ticket to Mumbai&rsquos Chhattrapati Shivaji Terminus. This time to make tracks for the quieter, historic corridors of the Unesco World Heritage Site&rsquos &lsquoHeadquarters Building&rsquo. Away from the public eye so far&mdashapparently since it was built 125 years ago&mdashthe administrative wing of one of the busiest and oldest stations in the country has now opened the doors to a heritage gallery of railway paraphernalia, some from the coffers of the Great Indian Peninsula Railway (GIPR). A magnificent staircase and an imposing domed ceiling&mdashmarkers of the building&rsquos Victorian Gothic Revival architectural style&mdashalso invite closer inspection. Add to that a bird&rsquos-eye view of the busy ticketing counters below, and you have more than enough to fill the short two-hour window (3&ndash5pm on weekdays) afforded by your Rs 200 ticket (Rs 100 for students). Chug along then to Mumbai.