Caswell-Massey pop up is now open at 312 Bowery at First Street. (First mentioned here.)
The space is a retail/exhibit combo celebrating 267 years of the American fragrance house, whose first NYC store opened in the 1860s. (Their flagship location on Lexington at 48th in the Barclay Hotel was around from 1926 until 2010.)
A Caswell-Massey rep told me that this outpost will be open through the December holidays and into early Spring 2020.