It may be one of Seattle's most scenic viewpoints, the top of the Alaskan Way Viaduct.

The state Department of Transportation wants to know what you'd do if you and your family or friends had the viaduct all to yourselves — with no cars and no other people — for half an hour. Celebrate a birthday? Make a marriage proposal? Stage a flash mob?

The DOT is sponsoring a contest offering one person and up to 24 friends the chance to win exclusive access to the viaduct's downtown section for 30 minutes on Oct. 22, the day after the southern mile of the viaduct closes for nine days for demolition.

To enter, answer the question: "What would I do with 30 minutes on the Alaskan Way Viaduct" in 100 words or less and send it to viaduct@wsdot.wa.gov by Sunday, Oct. 16.

The winner will be escorted to a private section of the viaduct for a quick party.

If you don't win the contest but still want to say farewell to the elevated highway, the state is sponsoring a commemorative walk Saturday, Oct. 22. A portion of the top deck near the stadiums will be open to watch as crews demolish large sections of the viaduct; visitors also can take home a commemorative piece of the structure.

The walk will be from 9:30 a.m. to 12:30 p.m. beginning at 1051 First Avenue South. Children under 18 must be accompanied by an adult.

Susan Gilmore: 206-464-2054 or sgilmore@seattletimes.com