That's an interesting question. I was going to guess CLU, but I was very wrong: there are native VAX and SPARC implementations, a Portable CLU implementation, and even a CLU-to-C compiler. Impressive for a language I hadn't heard of before today!

http://www.pmg.lcs.mit.edu/CLU.html

I would love some online tutorials/sandboxes for exploring these historical languages.

It wouldn't surprise me if all of these languages were alive in some way or other. There are MLs and APLs and Pascals alive and well.