Seattle’s once-barren Denny Triangle neighborhood has transformed into a forest of high-rises in recent years, thanks in part to Amazon’s huge multi-block campus there — and now the retail giant is looking to put up a treehouse.

Amazon’s newest office tower, a 17-story structure at 2205 Seventh Ave. in Seattle, is being designed with an “urban treehouse” theme in mind. Amazon, and the architectural team working on the building, on a site known as Block 18, released new images of the structure this morning ahead of a meeting of the city’s Design Review Board next week.

The building, designed by Seattle architecture firm Graphite Design Group, will have approximately 388,000 square feet of office space, 8,800 square feet of retail and 407 parking spaces. Today, the site is home to a hotel that has been serving as a temporary shelter for homeless services organization Mary’s Place.

Amazon’s buildings in the Denny Triangle stand out for their flashy designs, with the triumvirate of Amazon Spheres as the headliner, and this latest project is no different. The central feature is a staircase down the center of the building that resembles the ladder up a childhood treehouse, and the team highlighted it by setting it back from other parts of the structure.

Also in the new plans, Amazon breaks out how each piece of the building will be used. Collaborative spaces border the central staircase. Work spaces are distributed toward the outside of the building. On the top floor is a deck available to all building tenants, as well as a “birds nest” collaborative and gathering area.

The project represents Amazon’s fifth tower in the neighborhood. Amazon affiliate Acorn Development last December paid more than $19 million for the site, a half block along the west side of Seventh Avenue, between Blanchard and Bell streets.

Amazon planted a flag in the Denny Triangle neighborhood in 2012, when it dropped more than $207 million to acquire three blocks for its second campus in Seattle. Approximately a year later, Amazon spent another $52 million on a fourth block.

Amazon has completed or partially finished two blocks already — the Doppler building that opened in 2015 and the Day One building, which shares the block with the Spheres. The third and fourth blocks are under construction now.

The continued development of the Denny Triangle campus underscores Amazon’s bullish outlook in Seattle, even as it prepares to build a second North American headquarters in another city. In addition to this campus, Amazon has leased several million square feet of new buildings, including the iconic Rainier Tower, and a huge swath of space above the downtown Seattle Macy’s store.

Amazon is up to 541,900 employees worldwide, according to its latest quarterly update. That includes 50,000 people in Seattle, the same number of folks Amazon is looking to hire for HQ2.