I can think of any of number of reasons why I might not.

It’s late at night.
The ally is narrow and very confined.
Dodgy looking doorways with who knows what’s lurking behind.
Less than robust looking scaffolding.
Dark cloaked figures.

I can think of any of number of reasons why I might.

A shortcut between places.
A respite from the heavy rain.
Local pubs hidden away from transient visitors.
Photographic possibilities.

… under the Clock Tower in the Irish town of Mallow.

Photo: Robert Rath, ‘Walk This Way’, 0.8s f/6.3 ISO400 17mm