Contractor Willmott Dixon has handed the buildings over to Oldham Council and the Northern Roots charity.
Northern Roots is being developed across 160 acres of land next to Alexandra Park and is planned to become an urban farm and eco-park.
The new Welcome Building includes a café, shop and production kitchen, as well as two spaces for school visits, community events, meetings, exhibitions and performances.
Visitors will also have access to green spaces, orchards, community gardens, food-growing areas and an outdoor play area.
Manchester chef, food writer and restaurateur Mary-Ellen McTague has joined the project as its chef partner.
She will lead development of the café menu and support recruitment for roles including head chef. Produce grown on the urban farm will be used in meals served on the site.
The Forestry Skills Centre will provide training in areas including landscape management and crop growing.
Northern Roots said eight Oldham residents are already employed through the project, including five people who were previously unemployed.
The project aims to attract up to 300,000 visitors a year by 2030 and accommodate 4,500 school visits annually.
Plans also include 150 volunteering placements and support for up to 40 new businesses, with between 60 and 80 jobs expected to be created.
Environmental work includes plans for new woodland and wetland habitat, renewable energy generation and carbon storage.
James Kington, Director of Growth at Oldham Council, said: “This is an exciting milestone for both the project and for Oldham. These fantastic new facilities bring us one step closer to welcoming local residents and visitors from other communities across Oldham and further afield, to showcase everything the site has to offer.
“Whether you're visiting with family for a day out, enjoying the outdoor play area, learning new skills, attending an event, exploring nature or sampling fresh produce grown on site, Northern Roots will offer something for everyone.
“Together with Alexandra Park next door, it will create one of the borough's most exciting green destinations, attracting visitors, supporting jobs and helping more people connect with nature.”
Anna Da Silva, Chief Executive of Northern Roots, said: “For decades we've tended to think about health, regeneration, nature recovery, skills and economic growth as separate challenges requiring separate solutions. Northern Roots demonstrates that they are deeply connected.
“This project has been built on the belief that nature can be a powerful force for positive change, particularly in urban communities that have historically had less access to green space and opportunity.
“What makes Northern Roots different is that we're not simply creating a visitor destination. We're creating a place that improves lives, supports businesses, restores habitats, develops skills, strengthens communities and delivers measurable social value.
“When we open our buildings in September, we hope people will see not only what Northern Roots can achieve for Oldham, but what it could teach us about the future of urban regeneration across the UK.”
Willmott Dixon said its work on the development included 340 hours supporting unemployed people into work, 160 hours working with local schools and colleges and 103 weeks supporting apprentices and T-Level students.
Northern Roots is due to open on 19 September.
