Once hailed as the most elegant hotel south of San Francisco, the Mansion House in Watsonville, built in 1871, was considered past its prime in 1910. Owners Mateo and M. N. Lettunich, orchardists who also operated the Pájaro Valley's largest fruit packing business, moved the hotel in 1914 and hired James Patterson of San José to build a new structure which was to be known as the Lettunich Building.

Then called a "skyscraper", the structure was built of steel and reinforced concrete with twenty-seven offices on the three upper floors which were reached by electric elevator. Built in a record six months, the new Lettunich Building boasted electricity, steam heat and water throughout as well as the celebrated Cutter Patent Mail Chute. The exterior of the building, of concrete and enameled terra cotta, featured an ornament over the entrance made of fruits of the Pájaro Valley.

Banking had its beginning in the building with the Fruit Growers National Bank as a tenant in 1919. Fruit Growers sold to Liberty Bank in 1927 and that in turn became the Bank of Italy which later became the Bank of America. Bank of America remained until 1969 when it was relocated to Main and Fifth Streets. The Lettunich Building remains a central part of downtown Watsonville.