when was the company founded by philanthropist which  is Sellen Construction client established  
Sellen Construction:  Its clients have included Microsoft, Amazon.com, AT&T, Russell Investments, The Bill and Melinda Gates Foundation, and Vulcan Inc. Vulcan Inc.:  It was established in 1986 and oversees Allen's diverse business activities and philanthropic endeavors--from sports teams which include the Seattle Seahawks and the Portland Trail Blazers to conservation projects such as the Great Elephant Census, the Seattle Cinerama, and Museum of Pop Culture.
i don't know