Construction is progressing on Manhattan’s largest outdoor roof deck atop the ten-story 341 Ninth Avenue in West Chelsea. Tishman Speyer and the United States Post Office are working together to redevelop the 2.2-million-square-foot building, known as the Morgan North Postal Facility, which was originally completed in 1933 and occupies a full block from Ninth to Tenth Avenues and West 29th to West 30th Streets. Upon completion, the structure will not only boast a 2.5-acre landscaped rooftop, but also more than 5,000 square feet of ground-floor retail along Ninth Avenue and newly renovated and modernized office floors. CBRE represented USPS in prior negotiations with Tishman Speyer for the project. King Contracting Group is handling the removal and replacement of the main roof on the seventh floor, totaling 150,000 square feet.