To entice buyers to spend $1 million for one-bedroom apartments on the less glossy eastern edge of the Upper East Side, the builders of a shimmering glass tower going up at 91st Street and First Avenue advertise customized stone countertops, a private fitness center, "expansive sunrise and sunset views" - and the Second Avenue subway.

Now that construction crews have started work on the Second Avenue line after decades of delays, bullish real estate brokers and nervous neighborhood tenants alike expect New York's first new subway in 50 years to join the market forces that are driving Park Avenue-style prices farther east and replacing quirky Hungarian shops with high-end chain stores.

Ending commuters' long walk west to the Lexington Avenue subway will bring new cachet to addresses on Second Avenue and eastward - or at least that's what developers and real estate brokers are betting. Among them are the builders at 91st and First, who point to the subway's expected opening in 2014 and boldly declare that their tower, christened the Azure, stands at "the heart of the Upper East Side."