On the corner of Main and East Beach Streets, where the Lettunich Building now stands, was the Pacific Exchange Hotel built in 1856 by T.D. Alexander. By 1871 the owners decided that a larger and more modern hotel was needed and Thomas Beck was hired to draw up the plans. It was named the Mansion Hotel.

Many of the old hotel's registers have been saved and include such signatures as General Tom Thumb and Ulysses S. Grant. In 1900 it would have cost $2.00 to spend the night, and free busses would take guests to and from the train station.

In 1906, Mateo and M.N. Lettunich purchased the property. They decided to move the hotel north 110 feet and build an office building in its place. In 1914 the old hotel was jacked up and lowered onto a series of 100 feet long log rollers. As it inched along and one log would roll out from the back of the building, it would be picked up and placed under the front.

In 1978, the Mansion House was doomed for the wrecking ball but was saved when the owners donated it to the Pájaro Valley Historical Association. It has been sold various times since. The Mansion House is one of the oldest wooden buildings in the heart of downtown Watsonville.