Originally called “Overlea," this structure was built as a private residence for Mr. David Pepper and his family in 1893 and was not part of the Morris estate. Built by Wilson Eyre Jr., a well known residential architect of the time, it brought national attention to Philadelphia’s suburban architecture. The window variations, classical motifs and human figures seen in the ornamental details were typical of Eyre’s work. In 1948 the building was purchased by the Arboretum and re-named for Thomas Sovereign Gates, a former University of Pennsylvania President, who was instrumental in establishing the Arboretum. Gates Hall was acquired as an administration building and laboratory and it is still used in that fashion today.