zero :) - I was there with work for a few weeks - was put up in an excellent business hotel and took the tube to work with others daily. However this was years ago and I'm sure its all changed a bit. On the weekends I was basically on my own or with a couple others for part of a day... and I just saw it all. Just walking the streets lined with 900 year old buildings is amazing. I never did make it to the red-light area (happily married) but I hear its the best around. McDonalds had some crazy shrimp burger thing with a black bun :) - and generally speaking eating out was ridiculously inexpensive - found some great places on my own, but also did an excellent Argentinian BBQ place in the basement of a very old building with a co-worker - we had beers a-plenty as well as steak and other meats similar to Brazilian and total was like $20. I just really enjoyed the architecture - in particular the clock, a few cathedrals, some fancy bridge lined with statues and dudes playing the hurdy-gurdy in old-time garb. I can recommend getting little eat-while-you-walk fruit baskets from any of the street vendors - kind of a rip-off, but at the same time wonderful. Have fun!