The existing California Science Center Museum was not fitted with window washing fixtures and davits due to then budget issues. With the building completed over 15 years ago, the feature skylights and windows were in need of cleaning. We were retained by the State of California to develop and design a suitable window and skylight cleaning procedure using existing and new fixtures, davits and walkways. Our design team developed new triangulated cabling system to enable access for window cleaning of the large pyramidal skylight. Our design team also added exterior catwalks and window access panels to enable cleaning of all exterior windows. As part of the program, an OPOS program for unscheduled maintenance and window/skylight cleaning was developed for use by CSC Museum staff.