[PeterWhittaker]

Perhaps I am too much of a curmudgeon, but the example first sentence made me not care at all - not about Venice, but about the writer's approach, which seems to want to conjure breathless mystery about something I could easily look up on Wikipedia (or read in tl;dr comments in this thread).

It ISN'T Venice you need to make me care about, it's YOU! Why should I spend any of my time on you?

A good first sentence should make me care about your perspective, at least for non-fiction about subjects well-studied.

Fiction, obvs, differs. Scalzi's Old Man's War had such a great first sentence I devoured the series.