Born in Ohio, Greenleaf settled in St. Louis in the 1840s and began working as a carpenter and builder. In 1869 he opened an office on Olive Street with relative W.E. Greenleaf, a draftsman. Greenleaf is best known for designing the Romanesque Revival North Presbyterian Church (now SS. Cyril and Methodius Church), as well as several of the pavilions in Tower Grove Park. Greenleaf’s summer houses were designed and built between 1870 and 1872, and are recognized as contributing features in the park’s 1989 National Historic Landmark designation. The structures exhibit a remarkable versatility of styles and influences and include the Sons of Rest Summer House (the Sons of Rest Pavilion today) which was the largest of Greenleaf’s designs; the octagonal Children's Playground Summer House (the Old Playground Pavilion today); the eight-sided bandstand known as the Music Stand; the small, rectangular, Lily Pond Summer House (Lily Pond Shelter today); the Turkish Pavilion (originally designed to be a dovecot); and, the small-scale Well House (Photo 22).
Eugene Greenleaf died in 1881 in Jacksonville, Illinois, and is buried in St. Louis’ Bellefontaine Cemetery.