Algol is very important historically, but is quit dead these days. It introduced the flexible line systax, control structures and pesky semicolons that are common in most major languages now. There are a couple relevant examples in the notes: Prime Finder and Jensen's Device. The original definition is an elegant bit of work.

I'm not aware of any existing Algol compilers, but there is a simpler program called marst, which translates Algol into C, which can then be compiled. Marst is installed on Sandbox, and there is a local command algc which will compile Algol programs using the above two steps. Use the file extension .alg.