The Columbia Gorge Discovery Center shares space with the Wasco County Historical Museum in The Dalles, Oregon, making it a two-fer on the tourism front.
The Columbia Gorge Discovery Center is the gorge's official interpretive center, with exhibits about the ancient natural events that created the gorge, the wildlife and plants that you'll see when you explore the area, and the cultural history of the Native Americans who once called this area home. There are also trails around the property (some of which are paved and fully accessible) and viewpoints overlooking the river.
There are often temporary exhibits at the museum, as well as special events. A regular presentation on birds of prey with a live raptor show is usually a hit with kids, and there are guided nature walks available.
The Columbia Gorge Discovery Center is open daily from 9am-5pm, and the on-site cafe is open Tuesday-Sunday from 11am-3pm. Both are closed New Year's Day, Memorial Day, and Christmas Day. Admission is $9 for adults, $7 for seniors, and $5 for children ages 6-16. The facility is located off Highway I-84 near exit 82 in The Dalles, roughly 82 miles from Portland.