The Spheres (Amazon Spheres)

In the early 2010s Amazon began planning a large headquarters campus in Seattle's Denny Triangle, where it acquired three city blocks in 2012. The brief for the second building first called for a six-storey block of flexible offices and a meeting centre; it was replaced by a spherical conservatory that the firm NBBJ had been developing since 2012.

When the design was presented to the city's design review board in May 2013 the reception was mixed: praised as bold, it was criticised for offering no shelter from the rain, too little public access and a heavy energy demand for climate control. In August NBBJ replaced the steel supports beneath the glass with organic forms dubbed "Catalan spheres", and the board approved the scheme in October 2013 after minor changes to the understructure.

Construction began in 2015. The first steel pieces went up in February 2016 and glazing started in April. In May 2017 an Australian tree fern grown at the company's greenhouse in Redmond became the first plant to move in; in June a 17-metre Ficus rubiginosa nicknamed "Rubi" was lowered inside by crane. Jeff Bezos dedicated the complex on 29 January 2018 alongside Mayor Jenny Durkan, County Executive Dow Constantine and Governor Jay Inslee. Employees moved in the following day, when the public Understory exhibit also opened. Closed to visitors during the COVID-19 pandemic, the Spheres now welcome the public again.

The three intersecting domes fill half a city block on Lenora Street, between 6th and 7th Avenues, beside the Day 1 office tower. They range from 24 to 29 metres in height, the equivalent of three to four storeys. The shell is based on the geometry of the pentagonal hexecontahedron: its five-sided panels define the steel grid, which carries more than 2,600 panes of glass on roughly 560 tonnes of white-painted steel.

The central sphere, the largest, has four levels and about 300 m² of floor space, containing the cafeteria, the stair, the lifts and the restrooms. The stair shaft is lined with a four-storey living wall, which the official site puts at about 316 m². Tables, benches and meeting rooms seat up to 800 people, since the building is first of all a workplace. The design draws on biophilic principles, which seek to bring nature back into the built environment. During the day the air is held at 22 °C and 60 per cent humidity. The interior landscape was designed with the firm Site Workshop, and the building, often compared to the Space Needle, has become a landmark of the district.

The Spheres hold more than 40,000 plants from the world's cloud forests. The official site speaks of more than 1,000 species from some thirty countries, while other sources give 50 countries. The western dome is devoted to the Old World and the eastern dome to the New World. Among the 40 to 50 trees, the tallest is the 17-metre Ficus rubiginosa known as "Rubi". The living wall around the stair alone holds about 25,000 plants, including carnivorous species from Asia, while staghorn ferns, peacock plants, orchids and begonias fill out the planting.

The collection was grown over three years in a greenhouse in Redmond by Amazon's horticulture team, working with botanical gardens and universities around the world. Two flowerings of Amorphophallus titanum stand out in the building's short history: "Morticia" in October 2018, which drew 5,000 visitors in 48 hours, and the taller "Bellatrix" in June 2019.

The Spheres stand at the heart of Amazon's campus in the Denny Triangle, just north of downtown Seattle. The general public is admitted on the first and third Saturday of each month with a reservation made through the official website; the rest of the time the domes are reserved for employees. On the ground floor the Understory exhibit, free and with no booking needed, introduces the plants and animals found in the Spheres and takes 20 to 40 minutes to see. Pets are not allowed inside the domes. A visit pairs well with the Volunteer Park Conservatory on Capitol Hill.