Along with the sparkle and shine, the restoration crew left behind a grimy reminder of the station’s smoky past. In the northwest corner of the ceiling, crossing the teal-blue background and the arch over the West Balcony, there is a small, dark rectangle that was left untouched. Look up and find the crab, and near its claw you can still see the spot, almost 20 years later.

A sticky patina of water stains, train soot, dirt and grime had smothered the ceiling, but the key ingredient in the brown sludge was tobacco—decades and decades of cigarette smoke wafting up with no means of escape. To clean it all and still preserve the ceiling’s luster was painstaking work, using only mild sudsy water and gentle scrubbing with Q-tips.

The restored ceiling isn’t from 1913; that one had already fallen into disrepair by the 1940s. It was covered over with panels that recreated the original design (although some Grand Central purists insist the original puts this one to shame). Removing the panels and restoring underneath was considered, but they contain asbestos and removing them would have been nearly impossible in a train station that serves over half a million people a day. Besides the asbestos problem, the architects overseeing the restoration claim the original ceiling was already so damaged it was beyond repair.