(1875, Mortimer C. Merritt; expanded 1895) As early as the 1860’s, the West 20s above Union Square had a reputation as a shopping district for a new class of retail consumer, primarily women with disposable income and leisure time to spend on shopping for ready-made clothing and goods. The Hugh O’Neill Dry Goods Store is perhaps the most visible department store on this stretch of Sixth Avenue. With its domed corner towers and central pediment, it is among the finest examples of cast-iron architecture in the city. The original fourstory, French-inspired Renaissance Revival design was expanded in 1895 with a fifth floor. The domes and pediment were temporarily removed and then reinstalled on top of the addition. Adding stories or whole new bays on cast-iron fronted buildings was a fairly frequent occurrence, and pointed up the advantages of cast iron as a modular construction technology in which standardized, mass-produced facade components and ornament could be replicated and installed with relative ease.

In 1750, British naval officer Thomas Clarke bought a Dutch farm to create his retirement estate, named “Chelsea” after the Royal Hospital Chelsea in London. His property extended from approximately Eighth Avenue to the Hudson—its shore ran roughly along today’s Tenth Avenue—between 20th and 28th Streets. The estate was subdivided in 1813 between two grandsons; Clement Clarke Moore received the southern half below 24th Street while his cousin, Thomas B. Clarke, inherited the northern section. The two halves developed distinctly different characters due to the split. Today, Chelsea contains a variety of historic architecture, including some of the city’s most intact nineteenth-century residential blocks, significant commercial buildings, and industrial complexes near the Hudson River.