From the South:

1. Take I-5 North towards Seattle

 
2. Take the Seneca ST. Exit - Exit 165 - On the Left

 
3. Turn SLIGHT left onto Seneca ST.

 
4. End at 1200 5th Ave. (The IBM Building)

From the North:

1. Take I-5 South

 
2. Take the Union St Exit - Exit 165B

 
3. Stay STRAIGHT to go onto Union St.

 
4. Turn Left onto 5th Ave.

 
5. End at 1200 5th Ave. (The IBM Building)