Interesting idea. I think I may have read long ago (as a kid) that igloos have windows made of ice. Not sure. Update: just checked this: https://en.wikipedia.

Interesting idea. I think I may have read long ago (as a kid) that igloos have windows made of ice. Not sure. Update: just checked this: https://en.wikipedia.org/wiki/Igloo https://en.wikipedia.org/wiki/Igloo They can have windows made of ice blocks, says the article - see the "Construction" section.