The U.S. Army Corps of Engineers invites guests to visit The Dalles Dam Visitor Center and tour the dam this summer beginning tomorrow. The visitor center will be open Fridays, Saturdays and Sundays from May 6 through the end of September. The visitor center will also be open every day from May 30 through Sept. 3. Hours of operation are always 9 a.m. to 5 p.m.