Built in the Italianate style by tobacco merchant Francis S. J. Ronald in 1868, it was named for the Thomas Brennan family, who lived here from 1884-1969. A native of Ireland and an inventor, he and his wife, Anna, raised 8 children here. In 1912 an office wing in a Renaissance style was added for
their son, Dr. John Brennan. He lived here until his death in 1963.