[1] He was a philanthropist who served as a trustee and honorary president for the Art Institute of Chicago, becoming one of its benefactors by donating thousands of artworks.

From 1894 to 1896 they studied at the Bayerische Akademie der Schönen Künste (Royal Bavarian Academy of Art) in Munich, Germany and the Académie Julian in Paris.

After several years of study in Europe Allerton became dissatisfied with his abilities as an artist, burned his paintings and returned home to Illinois.

After the stock market crash of 1929 Adler′s work diminished and Gregg came to live at Allerton′s estate as landscape architect and business manager, a salaried position.

It is believed that Allerton and Gregg were involved in a same-sex relationship, at a time when the United States practiced social and legal discrimination against homosexuals.

The former Hawaiian Royal tropical estate, located on the island of Kauaʻi in Hawaiʻi, is now called the Allerton Garden.

After John Gregg Allerton's death it became part of the National Tropical Botanical Garden, with public tours.