The Columbia Gorge Discovery Center will celebrate its 20th anniversary on Sunday with free admission and a host of activities. The Center in The Dalles is the official interpretive center of the Columbia River Gorge National Scenic Area, and was dedicated in May 1997. Discovery Center marketing manager Susan Buce says everyone is invited to attend. There will be wildflower identification walks, raptor presentations, and Native American demonstrations. The Center will be open from 9 a.m. to 5 p.m., as it is every day.