Someone wanted to know what happened to the hole in Duval Street's 500 block, next to the San Carlos Theater:
The short answer is not much since the fire destroyed the businesses that used to live here. The fire last March was a rather big deal in the early hours:
As I recall there was an art gallery alongside the French pancake shop, whose remains are shown here:
Right now, between Margaritaville and the San Carlos there is some very attractive fencing and a large hole:
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Anyway back to the bet. This here is the 500 block of Prospect Lane.
I suppose technically it is one block long though it doesn't actually open into Applerouth Lane but you can certainly ride a Bonneville up Prospect from Fleming Street opposite La Concha (or The La Concha if you don't eSpeak eSpanish):
And as you can see it is unmarked, hence the bet suggestion. The one way sign actually refers to Fleming Street and points to Duval. If Prospect were one way it would soon get pretty jammed up.
Prospect is not, with the best will in the world, too terribly scenic. It is the backside of everything else. It's the back of the old Kress Building, which houses fast Buck Freddie's and Margaritaville:
And the back side of a department store isn't usually to be found decorating postcards. I spent many happy months here sorting out deliveries too and from Fast Bucks while enjoying the gastronomic leftovers from Margaritaville warming over in their dumpster nearby:

And the parking lot of the former Cuban Consulate is decidedly frosty as one might expect in a town where parking is at a premium. Appelrouth Lane is beyond the distant trees as shown in this previous essay: http://conchscooter.blogspot.com/2009/02/appelrouth-lane.html published here February 13th 2009.
So, having won the bet worded to your best advantage about Key West's least known alley, there is more one question to be answered. Why did the chicken cross the street?