AI powerhouse signs city's largest office deal so far this year Anthropic will anchor the north building of the Dexter Yard complex in Seattle's South Lake Union neighborhood. (CoStar) CoStar News June 30, 2026 | 8:29 P.M. Anthropic, the artificial intelligence giant that's behind record-breaking leases around the world, is extending its aggressive expansion streak to Seattle ahead of plans to go public.