At one minute past midnight on Sept. 16, a state landmark known by millions of motorists will go dark. Employees will say their goodbyes before the doors and off-ramps are barricaded at Maryland House, the Interstate 95 travel plaza in Harford County that opened in 1963. Within weeks, wrecking crews will level the neo-Georgian brick structure to make way for a new building, the flagship of an ambitious public-private partnership valued at a half-billion dollars. The same night, the smaller Chesapeake House in Cecil County will change as new vendors replace old ones. In a year, it too will come...