I love the city Vienna, one of my favourite musicians is Vienna Teng (not her real name) and because of these two things I like it. Vienna is one of those cities I get that people could want to name their child after, it's absolutely beautiful, so much culture and history, and it's so fresh and nice there. And Vienna Teng makes the most gorgous music...
Capital of Austria. It's a place name, so not a human name in my opinion.
The first thing I thought of was that ice-cream dessert, Viennetta, which isn't really a bad thing to think of when you hear a name. I think it sounds quite pretty. It's unusual, but still sounds quite familiar, and I think Vivie or Via would be really sweet nicknames if you were to use one. It's nicer than Sienna in my opinion, but also reminds me of Valentina and Verona, which I prefer.
Edited to add: I don't think it being a place name rules it out as a name, there are plenty of place names used as baby names. Off the top of my head: Paris, Aurora, Ireland, Harlow, Adelaide.
My first though is the sausages. My second is that trashy girl from "The Bachelor".