Roncesvalles, the name of Toronto’s Polish neighbourhood, is of Spanish origin, not, as I thought, French.
In Toronto it’s pronounced idiosyncratically as “Ron-says-veils”, and if it were a French name it would be more like “Ronh-se-vahl” (which I always figured was the “right” way to say it)…but Spanish is a whole new ballgame and I don’t know the rules!
A quick Google turns up a dictionary entry which says it should rhyme with “on the bias”. Ron-says-vye-us. Now, ask ten typical befuddled tourists at Dundas West Station, and you’ll get ten new pronunciations…!