What's up with "castles in Spain"?

OK, this is pretty trivial, but it is definitely in the spectrum of the Arts, so I’m putting this here.

There are several old popular songs that reference “castles in Spain” either as something to be desired, or something that isn’t as necessary as some people seem to think. Here are some examples:

*My Romance *-

“My romance doesn’t need a castle rising in Spain”

*Far Away Places *-

“I pray for the day I can get underway
And look for those castles in Spain”

*Autumn in New York *-

“Autumn in New York
You’ll need no castles in Spain”

There are probably others that I’m not thinking of.

So what I want to know is, what is the original to which all of these presumably refer? Or, alternatively, why Spain (except it’s easy to rhyme, but there must be more to it than that) rather than France or Bavaria?

Could it have something to do with this (apparently castles in Spain are the epitome of 19th-century romanticism)?

Your thoughts?

The most magnificent castle/palace in Europe is likely the Alhambra in Spain and it has been lauded by damn near everybody ( me included :wink: ) as a little slice of heaven. Moorish palaces/castles seem to have acquired a general reputation as sumptuous symbols of sybaritic delight