Man imprisoned in glass tower and doesn't age

[Rickelle]

I read a short story years ago that was my introduction to science fiction. It is still one of the best stories I've read but can't remember the title or the author (it was posted by a newsgroup member).

The details are a bit sketchy but it was about a man imprisoned in a newly designed glass jail cell where he could look out over the city but was unable to do anything else. Eventually it is realised that this man doesn't age at all and he watches as the world changes over centuries while he remains in this glass enclosure. Aliens come to the area and mankind is wiped out (I think) and they discover this sole survivor still enclosed in his jail cell. I can't remember what happened after that or even if I've got the details right, but would love to hear from anyone who can help.

If I remember rightly, the person who posted this story said the author was quite famous for his science fiction stories.

Rickelle