When the new arsenal commander, Franklin D. Callender took over in 1856, he requested appropriations to be set aside for a new storehouse.  His correspondence to the ordnance office in Washington show his interest in the aesthetic as well as functional aspects of the design.  He wanted a building with towers on all four sides to be used for flank defense in the case of attack by local citizens!  Two of the four towers were deleted and replaced with turrets at the final stage of the design.  This was probably justified from a functional point of view, however it certainly changed the monumental symmetry of the original design.   The clocktower was constructed from the fine Benicia sandstone which was very carefully cut and joined.  The exterior was done in a rough "rock-face" finish and the roof was of slate.

   The picture above was taken sometime in the 1890's  of the clocktower and the surrounding area.   
   The drawing to the left shows the clocktower as it was built in 1859.  It clearly shows the two towers. Click on the picture to see a larger more detailed view.

   These two photo's were taken in 1912 when the clocktower was almost completely destroyed by an explosion.  The picture on the right shows the inside of the building, which had to be totally rebuilt.  The outside walls and the front tower survived but only the first two floors were rebuilt.

       This is the clocktower as it appears today.  It is used for trade shows, art shows, community events and conventions.  
     The clock is operated by a mechanism consisting of an unwinding cable weighted by a cannonball and had to be re-wound every six days. In the 1950's the clock stopped working and was not restored until 1979.  David L Morgan, a member of the National Association of Watch and Clock Collectors of Diablo Valley returned it to service, however today no one winds the clock.