Hemisferic
We explored this building for the first time this year. It's quite a bizarre looking one from the outside. Its reflection makes it look much like an eye with an eyelid (see here) but that round dome in the centre is a vast Imax cinema. We saw a fifty minute film on the Hubble telescope and it was phenomenal seeing space spread out all across the domed ceiling like that. They show many other Imax films here but it is also used as a planetarium and laserium.
Oceanografic
Oceanografic was the sealife attraction we explored fully on our last visit a year ago. It's an open air zoo, in effect, focusing almost entirely on marine life, although there are some birds there in a giant aviary too. The various buildings represent different climates, everything from tropical oceans to the Antarctic. There are over 500 species of animal here and it is well worth a visit!
See Oceanografic at night here.
El Museu de les Ciencies Principe Felipe
The Science Museum is another attraction we visited last year. It features a lot of exhibitions but didn't have the same buzz that the Science Museum in London does. It is supposedly more of an entertaining exhibition of things like space, DNA, and interior design rather than being for educational purposes. I was rather surprised to find an exhibition entirely devoted to Marvel superheroes. Hardly scientific, but there you go. The exterior has been designed to look like a whale's skeleton apparently. I'd never really given it any thought, to be honest.
El Palau de les Arts Reina Sofia
This building is not normally open to the public although it is perhaps the most eye-catching structure of the whole City. This is the opera house of the set and is devoted to music and scenic arts. See the Palau lit up at night here.
L'Agora
The Agora is another building which is not open normally unless there is an event going on. It's a covered plaza with the purpose of hosting sporting events (e.g. tennis) and concerts. Exhibitions, conventions and meetings are held there too.
See the Agora at night here.
L'Umbracle
This one isn't a building so much as floral walkway featuring plants which are native to Valencia. Next to it are many interesting and bizarre sculptures. When we visited this summer every few yards was another sweet with a flag of the world on it! See the Umbracle at night here.
See the bridge at night here.
See the official website for the City of Arts and Sciences here.