I found this map of the city online -- it shows the "old city" where we spent most of our time. The city has sprawled out in all directions, and now has a population of something like 10-15 million.
There are over 1000 mosques in the city, which is the first thing that struck us as we drove into town on Friday morning. All the minarets dotting the sky line was actually quite ominous, and made an impression on both of us.
Anyway, our hotel is in the upper right corner of the map, near Taksim Square.
On Friday evening, our tour guide led us on a walk downtown. We took a subway from near our hotel down toward one of the bridges across the Golden Horn, and then walked across the bridge.
The bottom photo is from the bridge. The bridge is lined from start to finish with people fishing, just as a hobby. They catch small little fish that are apparently quite popular to eat. Guys walk along selling bait and something like homemade ouzo. Every time we walked on this bridge, day or night, it was full of people hanging out and fishing. It struck us as kind of odd because there's so much traffic over the bridge and I wouldn't want to vouch for the cleanness of the water, but I guess you can't be choosy if you live in the city.