The old city of Sana'a is an amazing place. The whole of the old city is a Unesco World Heritage site. The place is a maze of twisty roads, surrounded by multi storey mud brick "skyscrapers". My hotel was in one of these buildings, and I had the room at the very top (the sixth floor) with views on three sides over the old city. I spent a lot of time just looking out of the window of my bedroom, with sun rise and sun set being very special.
Most of the tourists in Sana'a seemed to be on organised trips, staying a few days in Sana'a and then heading out into the countryside to do hiking. Interestingly all of the tourists seemed to be French. No Brits or Americans!
The souq in the old city is another sight, you can buy anything here, from plastic buckets to entire glazed window units, ceremonial daggers to lumps of frankincense. The souq is interesting to wander around during the day, but after dark it really comes alive, with the lights from each stall spilling onto the streets!