Tallinn has such a beautiful skyline and leaving without a photo would be a shame. The best photo taking spot is located at a top floor of Radisson BLU hotel at a cocktail lounge called Lounge 24. It’s a restaurant / lounge that has a open air terrace on the 24th floor (hence the name of the lounge).
Since it’s a restaurant you would be expected to order at least a drink there but so many people go there just to take photos, I think they don’t mind anymore and you can just easily walk straight to the terrace at the back of the restaurant and ask kindly if you could take some photos. They never decline. And while you’re there taking your photos, you’ll probably be joined by others like you.
If you feel like having a cosmopolitan with your girlfriend or just a cold beer then the lounge is a fabulous place to do so, you’ll have amazing views over the city.