‘If you slip, you will still have three seconds to live.’
A more well-heeled crew concept, perhaps. Duskwall University students exploring the rooftops and seeing the world from a different angle.
A sought-after item in the setting might be a guide to the rooftops like The Night Climbers of Cambridge (source of the quote above): http://en.wikipedia.org/wiki/The_Night_Climbers_of_Cambridge
The author of Night Climbers rather spoils a simple enjoyment of that work by later writing Return to Responsibility: A New Concept of the Case for Fascism in the Post-War World — perhaps the PCs meet the guidebook’s author and he turns out to be a thorough cad.