Black Diamond (Royal Library), Copenhagen

If you have a penchant for books or modern architecture, the Black Diamond should be high up your list. A waterfront extension to the Royal Danish Library's old building, this iconic structure gets its (nick)name from its irregular-angled construction and polished black granite cladding – so polished, in fact, that you can actually see the blue sky and clouds reflected. The middle third of the front is a window that tends to gleam like a jewel after dark.

If the exterior is impressive, the interior is even more so. Anyone can go in and should. On the ground floor is a café and an upscale restaurant (the "Søren K.", for Søren Kierkegaard). You will also find a bookstore with some interesting works in English. Don't confine yourself to the ground floor, however. First look up at the atrium, and then take the escalator ramp up to the next level. After that, elevators or stairs are necessary. It's worth a trip to the top just to take photos of the atrium area and out the huge windows on the canal. Other things of interest include a rooftop terrace, exhibition spaces, a 600-seat auditorium/concert hall, and two museums – one displaying photography and another one cartoon art.

Tip:
After your visit, grab a coffee (or not) and sit out on one of the chairs on the waterfront, enjoying the goings on in the canal.