Jazz, gumbo, Mardi Gras, and James Gallier. All four have shaped New Orleans’ identity, vital components of a vibrant culture unlike any other. But only one of them—the least celebrated of the group—can claim to have shaped its built environment as well, as the visionary behind some of the city’s most significant structures.

Born James Gallagher in Ravensdale, Ireland, Gallier immigrated to the United States (via England) in 1832 at the age of 34. He spent two years in New York City before settling down in New Orleans, changing his last name to fit the Francophile city. While his life was tragically cut short in 1866 when his paddle-boat steamer capsized in a hurricane off the coast of Georgia, Gallier left an indelible impact on New Orleans, becoming one of its most influential architects of the 19th century.

We looked at the restoration of his namesake—New Orleans’ former city hall, drawn up by Gallier himself—in the Winter 2018 issue of Preservation magazine. Here are a few more of his finest designs:

Pontalba Buildings (pictured above)

Facing each other from opposite sides of New Orleans’ Jackson Square—an acclaimed public square in the heart of downtown—are identical three-and-one-half story, redbrick buildings with distinctive cast iron galleries lining their upper floors. Not only are the Pontalba Buildings two of the city’s most iconic structures, they’re also some of the oldest apartment complexes in the entire country.

The buildings were the brainchild of Micaela Almonester, Baroness of Pontalba, who wanted to give the square (then known as the Place d’Armes) a Parisian flavor. Though she first proposed their construction in 1846, work did not begin until 1849. That’s because the Baroness treated architects and builders poorly, making her difficult to work with. James Gallier contributed drawings and specifications for the project, but the Baroness declined to extend a contract to him.

Despite these issues, the Pontalba Buildings were completed in 1851, and influence New Orleans to this day. Their extensive use of cast iron, from the ornamental galleries to their cylindrical support columns, has made the material a staple of the city’s architecture. Today, the first floors have been commercialized, while the upper floors have retained their historic use as residential spaces.

Leeds-Davis Building

Cast iron also features prominently at the Leeds-Davis Building. Initially built as an iron foundry in 1852, much of the Gothic Revival-style structure’s facade consists of the metal, including its columns, window frames, and lintels. The columns support the two stories of stuccoed brick and pointed arches above.

In its days as an iron foundry, anywhere between 200 and 400 workers could be found casting and forging iron equipment used for harvesting sugar and cotton, making it the second-largest such factory in the South. The building now houses the headquarters of the Preservation Resource Center of New Orleans, which works to preserve historic places in the city.

Government Street Presbyterian Church

Constructed in 1837, Government Street Presbyterian Church in Mobile, Alabama, represents one of the oldest, least-altered Greek Revival-style places of worship in the United States. Its exterior, for which Gallier was responsible, is notable for its towering Ionic columns, complemented with pilasters on either side. To compensate for such an imposing facade, Gallier designed the church with identical rectangular panels above the two entrance doors, giving the impression of a larger doorway.

Inside, the church elaborates on its Greek Revival design. Curved staircases near the entryway lead from the basement to the gallery, which are decorated with Greek key molding and rosettes. A Corinthian tetrastyle backdrops a platform and pulpit that date back to 1893. But the building’s most striking feature is its deeply coffered ceiling. The diamond-shaped coffers, which are alternately illuminated and left dark, track diagonally across the ceiling, creating a visually engrossing pattern.