Lisbon Oceanarium

You are now at the heart of one of Europe's largest aquariums, where over 5 million litres of seawater hold thousands of marine creatures in a single massive tank. This is the Oceanarium, built as the centerpiece of Expo 98, the last world exposition of the 20th century. American architect Peter Chermayeff designed the building to look like an aircraft carrier floating on an artificial lagoon in Parque das Nações.

The theme of the expo was "The Oceans: A Heritage for the Future," and this aquarium became its lasting legacy. The central tank is what makes this place extraordinary. Sharks, rays, sunfish, and schools of smaller fish from different oceans all swim together in one enormous space. Around this main tank sit four smaller habitats representing the Atlantic, Pacific, Indian, and Antarctic waters, each with its own temperature and marine life.

The design deliberately blurs the boundaries between these sections, creating the impression that all the world's oceans flow into one another. Over 1 million people visit each year, and in 2011, a second building opened to house temporary exhibitions.