Pantheon Atlas LLC, the US-led investment vehicle behind the project, announced Pantheon AI at the Three Seas Initiative Summit in Dubrovnik on April 28, with US Secretary of Energy Chris Wright among those in attendance alongside 13 presidents and prime ministers.

The campus will be built in Topusko, 45 minutes from Zagreb, on a 310-acre site expandable to 450 acres. It is designed to deliver 1GW of total capacity and 800MW of usable IT load, built in accordance with Nvidia GW-Scale AI Factory standards. Construction is scheduled to begin in early 2027, with the facility expected to be fully operational by the first quarter of 2029.

The project targets above Tier IV resilience, a standard its developers describe as unique in Europe at a moment when established data centre hubs across the continent are operating below 8% vacancy and facing significant grid connection delays. Electricity demand for data centres across Central and Eastern Europe is projected to grow three to four times by 2035.

Power will be supplied entirely by renewable energy, delivered through an on-site 500 MW solar plant and 8,000MWh of battery storage, to be developed by Greenvolt International Power, a European renewable energy developer majority-owned by KKR, which has signed a letter of intent for the project.

The site’s transmission infrastructure, four independent 400kV lines, is designed to enable up to 5.2GW of new renewable energy integration onto Croatia’s national grid.

Connectivity is provided by four independent fibre routes across three major EU corridors, with the GreenMed subsea cable extending reach to Milan by 2028.

“We have assembled a transatlantic partnership to solve one of the most pressing challenges in global digital infrastructure: enabling hyperscale operators to meet AI-driven demand at scale,” said Ryan Rich, managing partner of PantheonAI.

“We have lined up the power, fibre, regulatory stability, and institutional support to solve that problem in Europe, and we will establish Croatia and Central Europe as a premier destination for world-class digital infrastructure.”

The campus is expected to create 1,500 permanent jobs on completion, with a further 3,000 roles during the construction phase. Sisak-Moslavina County has formally recognised the project as being of special importance to the region.

Key partners include Eastdil Secured on project advisory, Parsec Lab on data centre design and engineering, Končar Group on substation development, and Latham & Watkins and Hodgson Russ as legal counsel, with PwC and KPMG acting as financial advisors.

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