Exterior work is progressing on 509 Third Avenue, a 35-story residential tower in Murray Hill. Designed by Ismael Leyva Architects and developed by Kahen Properties with Lalezarian Properties under the Third and Thirty Four LLC, the 386-foot-tall structure will span 166,917 square feet and yield 229 units with an average scope of 692 square feet, as well as 8,253 square feet of retail space and a 30-foot-long yard. Charlton Development Group is the general contractor for the project, which is located at the corner of Third Avenue and East 34th Street.