Work is progressing on the addition and partial residential conversion of the 99-year old Crown Building at 730 Fifth Avenue. Originally designed by Warren and Wetmore, the 26-story structure has a rich history that includes serving as the original home of the Museum of Modern Art. The current transformation into Aman New York, a mixed-use hotel and residential property, is designed by Jean-Michel Gathy and is being developed by OKO Group. Renderings released last fall reveal the interiors of the building, which will house the Aman hotel from floors four through 24. The 22 condominiums are planned to span 95,000 square feet, for an average of more than 4,300 square feet apiece. Douglas Elliman Development Marketing is handling sales of the 22 condominiums.