Robert Henderson Robertson (April 29, 1849 – June 3, 1919) was an American architect and a pioneer of the early New York skyscraper. In the Flatiron District, just north of Union Square, he designed the American Woolen Company's headquarters at 225–233 Park Avenue South — an elegant 1909 building with a limestone base, terracotta ornament, fine copperwork, and a tiled mansard roof.
Born in Philadelphia in 1849, Robertson built one of the most varied careers of his era, ranging from grand churches and Vanderbilt-family estates to some of the earliest steel-framed towers in Manhattan, including the soaring Park Row Building downtown. His Park Avenue South building survives today as a distinguished commercial address, recently renovated and reconnected as a single property spanning 225 and 233.
| Full name | Robert Henderson Robertson |
| Born / Died | April 29, 1849 / June 3, 1919 |
| Profession | Architect |
| Active in Flatiron | 1909 (the American Woolen Building, 225–233 Park Avenue South) |
| Known for | The Park Row Building, the American Tract Society Building, the American Woolen Building at 225–233 Park Avenue South |
| Key Flatiron location | 225–233 Park Avenue South (the American Woolen Building), just north of Union Square |
| Notable legacy | Designed the American Woolen Company headquarters on Park Avenue South and helped pioneer the early New York steel skyscraper |
Who Was Robert?
Robert Henderson Robertson was born in Philadelphia in 1849 to Scottish parents and educated at Rutgers College before entering architecture. He became one of the most sought-after designers of the Gilded Age, working across an unusually wide range of building types — churches, libraries, civic institutions, country estates, and the new commercial skyscrapers that were transforming Manhattan.
Early in his career he practiced in partnership with William Appleton Potter, designing summer cottages along the Newport and New Jersey coasts and major institutional buildings at Princeton and Brown. He went on to become a favored architect of America’s industrial titans, designing buildings for the extended Vanderbilt family, including work at Shelburne Farms, and the Adirondacks Great Camp Santanoni.
Robertson is especially important as a pioneer of the steel skyscraper. His Park Row Building, completed in 1899, was for several years the tallest office building in the world. He also designed the American Tract Society Building and numerous churches across New York. He died in 1919 at an Adirondack lodge he had himself designed, leaving a body of work remarkable for both its range and its technical ambition.
Robert Henderson Robertson's Connection to the Flatiron District
In 1909, the American Woolen Company commissioned Robertson to design its New York headquarters at 225 Park Avenue South, just north of Union Square, with an adjoining building at 233 Park Avenue South directly to the north. The American Woolen Building presents an elegant face to the avenue: a limestone base rising to terracotta ornamentation, refined copperwork, and a handsome tiled mansard roof that crowns the composition.
The building reflects Robertson’s mature command of dignified commercial architecture, applied to the booming corridor that Park Avenue South had become. A century after it was built, the property was carefully renovated, with 225 and 233 Park Avenue South reconnected into a single Class A office building — a modern arrival sequence and lobby inserted while preserving the historic exterior that Robertson designed. For the neighborhood, it is a living example of how a Gilded Age building can be given a contemporary second life.
Legacy and Impact
The American Woolen Building remains one of the most graceful structures along Park Avenue South, its mansard roof and copper detailing a reminder of the elegance Robertson brought to commercial work. Its recent renovation, joining 225 and 233 into a single property while preserving the historic facade, has secured its place in the neighborhood for another generation.
Robertson’s broader legacy is significant. As one of the architects who helped develop the steel skyscraper — most dramatically in his record-setting Park Row Building — he stands among the figures who made the modern Manhattan skyline possible. His Flatiron-area building gives the district a tangible connection to that pivotal moment in architectural history.
A century after Robert Henderson Robertson designed the American Woolen Building, 225 and 233 Park Avenue South were reconnected into one property — its historic facade preserved, its life extended.
Key Facts Worth Knowing
- 1849: Robert Henderson Robertson was born in Philadelphia to Scottish parents.
- 1899: His Park Row Building was completed and stood for years as the tallest office building in the world.
- 1909: The American Woolen Company hired Robertson to design its headquarters at 225 Park Avenue South.
- The building features a limestone base, terracotta ornament, copperwork, and a tiled mansard roof.
- 1919: Robertson died at an Adirondack lodge he had himself designed.
FIND THEIR LEGACY TODAY
- 225–233 Park Avenue South (the American Woolen Building) — Robertson's elegant 1909 commercial building just north of Union Square, recently renovated as a single Class A property.
- Park Avenue South near East 18th–19th Streets — the corridor where the American Woolen Building's mansard roof and copper detailing are best seen.
- The Park Row Building, 15 Park Row — Robertson's record-setting early skyscraper downtown, for anyone tracing his pioneering tall-building work.
Explore More of Flatiron's History
→ Flatiron District Architecture Guide — The architectural legacy of Park Avenue South, where Robertson's American Woolen Building still stands.
→ Flatiron District History — How Park Avenue South north of Union Square grew into a major commercial corridor during Robertson's era.
→ Ladies Mile Flatiron — The historic shopping corridor just blocks from Robertson's American Woolen Building on Park Avenue South.
→ Gilded Age Social Clubs in Flatiron — The club culture that flourished in the same era Robertson was designing some of New York's earliest steel skyscrapers.
In Plain English
Robert Henderson Robertson was an American architect and a pioneer of the early steel skyscraper. In 1909 he designed the American Woolen Company headquarters at 225–233 Park Avenue South, just north of Union Square. The building, with its limestone base and tiled mansard roof, survives today as a renovated commercial property.
Frequently Asked Questions About Robert Henderson Robertson
Q: What did Robert Henderson Robertson design in the Flatiron District?
A: In 1909 Robertson designed the American Woolen Company headquarters at 225 Park Avenue South, with an adjoining building at 233 Park Avenue South to the north. The two now operate as a single renovated commercial property just north of Union Square.
Q: What is the American Woolen Building known for architecturally?
A: The building features a limestone base, terracotta ornamentation, fine copperwork, and a distinctive tiled mansard roof — an elegant example of Gilded Age commercial design on Park Avenue South.
Q: What is Robert Henderson Robertson most famous for?
A: Robertson is best known as a pioneer of the early steel skyscraper. His Park Row Building, completed in 1899, was for several years the tallest office building in the world.
Q: When was Robert Henderson Robertson born and when did he die?
A: Robertson was born in Philadelphia on April 29, 1849, and died on June 3, 1919, at an Adirondack lodge he had designed himself.
Q: Can you visit Robertson's American Woolen Building today?
A: The exterior of the building at 225–233 Park Avenue South is freely visible from the street. The interior is a private Class A office property and not generally open to the public.