Gender of nouns in French and Spanish

In French and Spanish, nouns (I'm excluding pronouns here), including inanimate objects, have a gender associated with them, unlike in English.  In English one does not say that the chair is feminine or that the pencil is masculine, but one does so in French (la chaise; le crayon) and in Spanish (la silla; el lápiz).

In a French class years ago, one English sentence assigned for translation into French included "casbah".  That word had become rather more well-known from the Rock the Casbah song by The Clash.  That being pre-World Wide Web times, we students rummaged through assorted paper dictionaries, and it seems that I, along with every other student, came up with nothing.  It further seemed that we all followed our instincts (which in retrospect seem to have had no logical underlying rationale), and gave it a masculine gender ("le casbah"), only to all simultaneously groan while correcting each others' translations as the professor told us (with a wry smile of satisfaction?) that it was la casbah (feminine).

In French some word endings normally indicate a particular gender.  Words ending in -ette, for instance, are almost always feminine.  However, I will never forget that le squelette (skeleton) is masculine, having read in Harper's Grammar of French (a very nice book!) years ago that it is one of the rare exceptions.

In French some nouns have different meanings in a masculine versus a feminine form.  Tour can be masculine or feminine.  One meaning of le tour is turn; one meaning of la tour is tower.  I'm not sure if there are similar such words in Spanish, though I think I will ask a native speaker soon....