Beats me.
Something to do with a water supply?
Answers on a postcard, please.
Bonus -
Being a construction of your humble blogger Tepid Halibut, with the aim of posting one vintage slide image per day, from now until Kingdom Come. (Or until Mr Halibut gets bored.)
Curious. This box had a series of Slide Mounts, each with a 35mm Black and White negative mounted in them. How rare. The seller claimed that they dated from 1937...and that might be reasonable.
This image had no description, but appears to be a floating dry-dock, so... COULD be the USS ARD-1. Or maybe something else.
Bonus :
Today's tedious slide was selected from the box marked "Rotten Holiday", and my initial thought was "That's possibly The Rock of Gibraltar."
But, No. It's a completely different shape.
Any suggestions?
Bonus -
The only info on this slide was "Oaxaca 1984", so ... Mexico, and some sort of market.
But what is the product? Bread? Leather? Tortilla?
Any advice would be welcomed.
Bonus - A 1000 years of ancestral connections in the European royal families
There's a band or musical group in the background, and the squeeze-box is easy to spot.
But what are the other two guys playing? It looks like some sort of snorkel-kazzoo, or maybe some sort of jew's harp?
Can anyone help?
Bonus -
Clearly, there is a facial resemblance of L Ron Hubbard of those wacky old, Scientologists ... tho' this may be a relation rather than LRH himself. But what of the items in the background. Why would someone have a bowl of Sump Oil on top of their clothes dryer?

A very black slide, with no information on it. Which is a pity, as I rather like this structure.
I'm guessing it's a public building, and the geometrical style make me thing Islam or the Middle East. Or maybe Moorish influences in Spain.
Anyone got an educated guess??
Bonus - Continuing the architecture theme... Detroit in ruins