The book I started but never finished is War and Peace by Leo Tolstoy. I'm a lawyer in São Paulo, in Brazil, and I started it about two years ago on a sort of personal challenge.
The reason I picked it up was a conversation with my uncle Paulo, who's a retired literature professor. At a family lunch he said, half joking, that nobody could call themselves well read without finishing War and Peace. I'm quite competitive, so the next day I bought a thick Portuguese translation and announced to everyone that I'd read it within three months.
The novel follows several aristocratic Russian families during the wars with Napoleon at the start of the nineteenth century. There are balls and love affairs in Moscow and St Petersburg, and then long descriptions of battles. I got through roughly the first third, which I actually enjoyed in places. One character, Natasha, is very lively and charming, and some of the family scenes are surprisingly funny.
There were a few reasons I didn't finish. The first was the sheer number of characters. Many of them have several names, and I constantly had to check a list at the front to remember who was who. Second, there are long chapters about military strategy and philosophy, and after a twelve-hour day in court, I'd fall asleep after two pages. And finally, I think I started it for the wrong reason. I was reading it to prove something to my uncle rather than because I wanted to. It's still on my bedside table with a bookmark in it, though, so I haven't given up completely.