I recently stumbled upon NASE A60, an open source Algol 60 interpreter.
Having learned a more “modern” Algol (on Burroughs computers in the early/mid 80’s), I think it’s kind of neat to revisit this language, which, according to The Retrocomputing Museum, is “the common ancestor of C, Pascal, Algol-68, Modula, Ada, and most other conventional languages that aren’t BASIC, FORTRAN, or COBOL.”