Crews next week are expected to start building the exterior walls of the joint YMCA and YWCA building on North Monroe Street. Those block walls will house aquatic and fitness centers, child care, community gathering areas, and services for teens, job seekers and victims of domestic violence. Although construction was delayed, the YWCA hopes to occupy the 80,000-square-foot campus, at 930 N. Monroe St., in April 2009, said Monica Walters, YWCA executive director.