It all started with a helium balloon ride.
Nearly two decades ago, the head of real estate at Vertex Pharmaceuticals was visiting Fan Pier. At the time, the 21-acre site in Boston was not much more than a windswept stretch of parking lots, bookended by the federal courthouse and the then-new waterfront home of the Institute of Contemporary Art. Developer Joe Fallon’s namesake firm used the balloon to rise up above the site and show off the views to potential tenants.