Wikipedia's picture of a double rainbox (left, credit) is lovely, but mine was even better. The secondary rainbow was better defined, and I think I counted nine distinct bands in the primary. It arced, like this picture, from ground to ground.
I wasn't in a beautiful Alaskan national park, I was leaving my office in Roseville, Minnesota. There'd been a downpour, but the rain was now steady but widely spaced, an odd pattern I don't see much. The sun was at about 25 degrees above the horizon, and the western sky had cleared, so the light was completely unobstructed.
I stood and watched in amazement. It lasted only about four to five minutes, then the secondary began to fade. I phoned home when I saw it, but it couldn't be seen even 15 miles south of me. It was a private show.
I don't think I've ever seen a rainbow like that, and perhaps I never will again. It was just one of those odd, unexpected gifts, like a letter from an old friend.