Half of it--lower end--is more or less in ruins.

There are old houses there which aren't tenanted.

Back of these houses are courts and alleys and queer entries, leading on one side to the river, and on the other to side streets.

A man could be lured into one of those places and put out of the way easily and quietly enough.

Or he could be shot by anybody lurking in one of those houses, and the murderer could be got away unobserved with the greatest ease.