One of my favorites.
I'm reading Shriek: An Afterword by Jeff VanderMeer. It's quite dense and challenging without a strict structural framework. Very meandering and there are two conflicting viewpoints throughout the book, with sprinklings of articles. It's about a fictional city called Ambergris which is built on the ruins of a race of mushroom people. The main story deals with a historian and his sister, who is writing his biography. It's one of the more difficult books I've read since Viriconium by M John Harrison, which is another book about a particular city. Actually a huge influence on the Ambergris books.