London and New York-based startup backed by Index Ventures says its systems compress weeks of site assessment into hours
Build, a startup founded by architect James Stirrat-Ellis and AI researcher Ben McClusky, has raised $8.5 million in seed funding led by Index Ventures, with participation from Pebblebed, Puzzle Ventures and Tiny.vc. Angel investors include OpenAI chief financial officer Sarah Friar, Blackstone chief technology officer John Stecher, and figures from Meta AI Research and Google Maps.
The company applies AI to infrastructure development workflows — site sourcing, technical due diligence, power assessment and early-stage design — that have traditionally been handled through sequential, largely manual processes. Build claims its platform reduces due diligence timelines by more than 95%, drawing on data from over 1,600 sources to evaluate planning, environmental, power and political constraints in parallel rather than in sequence. The company says it has been deployed across more than 100 projects in 15 countries for governments, Fortune 500 companies and institutional real estate groups including Tishman Speyer.
The business model is notable in that Build sells the output — completed development work — rather than software licences. Its AI systems handle thousands of tasks simultaneously, but every client deliverable is reviewed by human operators before it goes out. The company describes this as “agentic real estate”, a term it uses for the longer-term ambition of automating the development lifecycle from site selection through permitting, engineering, pre-construction and asset management.
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Stirrat-Ellis previously worked at Heatherwick Studio on projects including Changi Airport Terminal 5 in Singapore. McClusky’s background is in multi-agent systems and reinforcement learning. The wider team includes infrastructure specialists drawn from Blackstone, Tishman Speyer, Starwood Capital and JP Morgan, alongside people with direct data centre development experience.
“The industries shaping the physical world have spent decades trapped in process instead of creativity,” said Stirrat-Ellis. “By removing that operational burden, we can help teams move faster, make better decisions and deliver better infrastructure.”
The funding will go toward expanding Build’s engineering and infrastructure teams, accelerating R&D and extending its presence across North America and Europe. The company is headquartered in New York.
