With the placement of the influential IRT Third Avenue Elevated train, Garvin was immersed in designing many surrounding structures during the borough's increasing growth at the turn of the 20th century.

Of his architectural contributions the Haffen Building;[2] the Fire House, Hook and Ladder 17; and the Bronx Borough Courthouse[3] have all become New York City landmarks while the latter a US National Historic Place.

As the IRT Third Avenue Elevated Train was being constructed in The Bronx in 1897, and New York City consolidated in 1898, there was an enormous growth of population and financial investment.

Garvin, as well as several contemporary architects, designed single-family town houses, multistory apartment homes, and various business or manufacturing establishments.

Founders of the Haffen Brewing Company and the Dollar Savings Bank of the City of New York, The Haffen family was one of the main families of the Bronx, having made essential contributions to the physical and social infrastructure of the borough including surveying and laying out of parks and the streets, developing real estate, and organizing of a number of civic, social, and financial institutions.

He reached out to a former colleague of his, architect Oscar Florianus Bluemner, a German émigré (of Prussia) who had been a prize student at Berlin’s Royal Academy of Design, who also studied in Paris.

Though the story not absolute, it is speculated that Garvin offered to share fees and credit for their combined efforts in return for an acceptable building.

[5] Bluemner sued for $20,000 and argued that he was the true author of the design and not Garvin, who according to him was incapable of drawing "the plans for a big thing like the new Court House to save his life.

"[6] Garvin in his defense said that,"In the first place, only the model has been adopted by the Municipal Art Commission, subject to the presentation later on of the working plans.

Bluemner stated that Garvin approached him because he was in need of completing the design for the courthouse and he would give him equal credit and pay for their collaboration.

John Purroy Mitchel,[7] a young crusading lawyer who was attempting to advance his career by investigating municipal corruption, preyed on Bluemner's involvement with Garvin.

Bluemner, continued to help Mitchel, who possibly promised him a civil career in architecture under his administration, to oust the then Queens Borough President.

However, due to the controversy in court and political maneuvers from interested parties to decrease funding for the courthouse, construction extended for nearly ten years.

The public scandal called into question Garvin’s abilities as an architect, and whether it was his association with the Haffen family that had fueled his success.

Tired of all the years spent in court, and known to be full of humor, in 1909 he sarcastically replied to each, knowing that Mitchel was using them to move up in office.

In 1905, for the local Democratic organization, Garvin designed the Jefferson Tammany Hall, at the southwest corner of 159th Street and Elton Avenue.

In 1906 he designed the Fire House, Hook and Ladder 17 (1906–1907) at 341 East 143rd Street, a combined Beaux-Arts and Neoclassical architecture that has become a New York City Landmark.

When Garvin died on September 3, 1918, he was honored by many Bronx civic leaders, including then Borough President Henry Bruckner.

Max Hausle (1870–1943), one of Garvin's associates, along with Joseph H. Freedlander would go on to build the Bronx County Courthouse Garvin created numerous buildings, mostly in groups, in the neighborhoods of North New York (associated today as Mott Haven),[notes 2] Melrose, and Morrisania (or North Morrisania) in Bronx.

Some of Garvin's work that still remain, which only needs refreshing, in addition to the three landmarks include:[15][16][17] In studying the 1902 Beaux-Arts Haffen Building and looking clearly at the entrance-way on Third Avenue, the archway and linear features can be seen at the base of the Bronx Borough Courthouse.

Meanwhile, the second level of the courthouse and choice of stone work and overall layout for the entire building is put into serious argument by academic observers.

While debates have persisted as to who in fact designed the building, maybe it is time to equally recognize both under landmark status, along with Jules Edouard Roiné for his statue of Lady Justice, for contributing and making a fine example of combined Beaux-Arts Classicism and Art Nouveau architecture.