Thornton Tomasetti Share: Structural Engineering Thornton Tomasetti Visit Website 1500 4th Avenue Suite 450 Seattle, Washington 98101 (206) 336-4100 About Map About Engineering design, investigation and analysis services to clients worldwide on projects of every size and scale. We are 100% employee-owned firm of 1,500 engineers, with a local Seattle office of 12. What's Nearby? Distance: 5 10 15 20 25 50 mi.