The George Washington National Masonic Memorial is a handsome 10-story tower loosely based on the design of the Lighthouse of Alexandria in ancient Egypt.
If you go:
You can access the first two floors free, and see some displays about the Shriners' work on behalf of children, as well as artwork depicting Masonic history.
Links:

110 Callahan Drive
Alexandria, Virginia 22301 USA
Phone Numbers:
Information
+1 (703) 683-2007
+1 (703) 683-2007
FAX
+1 (703) 519-9270
+1 (703) 519-9270
Gift Shop
+1 (703) 549-9234
+1 (703) 549-9234