Inside Riverside Boulevards Most Expensive Penthouse That Just Sold For $18... New York City's Waterline Square is a gem on the Upper West Side and its penthouse di[...] June 14, 2019 / Natasha Bazika / Tags: Alex Stupak's Empellon, Hudson River, luxury condo, luxury penthouse, Luxury Residential Apartment Living, manhattan, Mathews Nielsen Landscape Architects, New York, nyc penthouse, Upper West Side, waterline square, Yabu Pushelberg