“The teacher’s son’s classroom” may lack elegance, but is surely better than the roundabout “La salle de classe du fils du professeur.” Similarly “John’s sister’s programme” is more succinct than “El programa de la hermana de Juan”.
Pragmatic German and Nordic languages simply add “˜s’ to denote the genitive: Deutschlands Wetter; Danmarks kong; Sveriges huvudstad; while Romance languages have to resort to a variety of forms…
Heartless marauding northern European cultures may have certain advantages with words: economy, for example. See Richard D. Lewis’s article “The Possessive Apostrophe” at his Cross-Culture. Don’t get the elegant Mr. Lewis wrong, though. Read the whole thing. It starts with the Birmingham (England) City Council’s removal of the possessive apostrophe from street signs. No kidding. Them Brummies.
Birmingham, above, is like Pittsburgh USA–just more pretentious.