Ideally I'd like to have a map of all of them in Constantinople.
Best Answer
All of the maps I can find of all of Constantinople seem to be focused on finding the Animus fragments, and not the Templar Dens, unfortunately.
The templar dens are pretty easy to locate, however. Each one is marked on your map from the start of the game, I believe. The icon looks a little odd, like a castle with three spires. (I almost think they look like tiny top-down spaceships, like in Galaga or similar) They often overlap with the "eagle" viewpoint icon.
If you go into the map's filter options, you can see what each icon represents, and you can toggle off all of them except for the Templar Dens, which should make finding them on the map super easy. When you're in the area of a Templar Den, you'll know for a number of reasons:
Shop icons are replaced by padlock icons, indicating that you can't buy the shop until you remove the den
You'll see "castle tower" icons (similar to the rook in chess) which indicate sniper hideouts
The map area around the den is in red, indicating it is a restricted area.
Here's a screenshot provided by Jeff Mercado and poorly edited by me. We've cleared the dens, so they show up with a different icon (an Assassin logo) - if you haven't cleared the dens yet, they'll show up like the icon above:
Keep in mind that you'll only be attacked if your Templar Awareness meter hits max and stays there for a given amount of time. Just kill officials and bribe heralds every time you do something to raise it, and you'll never have to worry about being attacked in the first place.
(One thing to note that's a big difference from previous games - renovating property seems to add about 25% to your meter! It's really easy to max out if you're not careful. Also, liberating a den in the first place seems to max it out every time, but you seem to have a few minutes to lower it before you risk an attack.)
I had no trouble doing all these immediately (beginning of chapter 3, I believe I did it) and in fact you can even max them all out in that chapter - unlike previous games, you can access pretty much the entire city except the very small Arsenal district from the very beginning.
What you might be missing, though, is that you can only have one mission at a time open. There doesn't appear to be any way to influence which den's mission will come up, but when you finish one, if you have a level 10 Assassin, the next one should crop up. This also goes for the level 14 missions as well - you have to take them one at a time. (Those are extra obvious because the Den Leader shows as on a mission in the assassin's interface even though they're actually still there.)
Best Answer
All of the maps I can find of all of Constantinople seem to be focused on finding the Animus fragments, and not the Templar Dens, unfortunately.
The templar dens are pretty easy to locate, however. Each one is marked on your map from the start of the game, I believe. The icon looks a little odd, like a castle with three spires. (I almost think they look like tiny top-down spaceships, like in Galaga or similar) They often overlap with the "eagle" viewpoint icon.
If you go into the map's filter options, you can see what each icon represents, and you can toggle off all of them except for the Templar Dens, which should make finding them on the map super easy. When you're in the area of a Templar Den, you'll know for a number of reasons:
Here's a screenshot provided by Jeff Mercado and poorly edited by me. We've cleared the dens, so they show up with a different icon (an Assassin logo) - if you haven't cleared the dens yet, they'll show up like the icon above: