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The Earth Centre – Yorkshire's answer to the Millennium Dome – opens to the public tomorrow. The first of the Millennium Commission's 14 landmark projects, it is a self-professed theme park with a serious message for its visitors.

The aim of the park, says the centre's chief executive Jonathan Smales, is to popularise the idea of sustainability. So, the £42m first phase serves up a bubbling stew of visitor attractions spread over 14 ha of Yorkshire hillside. Ancient methods of soil tilling are bundled together with futuristic high-tech electronic gadgetry and surreal new age imagery. The scale stretches from global warming to how to treat your grass clippings.

Symbolism is writ large in the main exhibition gallery, where rotating glass-fibre globes the size of small houses are split open to reveal empty bottles, discarded syringes, industrial rubbish and other detritus of mankind.

The Earth Centre is itself a supreme example of reclamation. The hillside site at Conisbrough on the banks of the River Don once accommodated two collieries and a limestone quarry that employed 10 000 people. They were finally closed in the 1980s. The two slag heaps they left have since been grassed over and 67 000 tonnes of sewage sludge, top soil and farmyard manure trucked in to create a fertile, rolling garden landscape.

In the same spirit, the buildings and basic utilities of the Earth Centre have been conceived as live exhibits of sustainable development. The main gallery devoted to Planet Earth and designed by Feilden Clegg Architects is a massive insitu concrete structure that burrows into the hillside to provide a stable, low-energy internal environment. Tempered air is circulated in a concrete basement labyrinth inspired by the ancient Roman hypocausts, and the limestone cladding was transported just 500 m from the neighbouring quarry.

Another building, designed by Alsop & Störmer, turns sewage treatment into a public spectacle. The process starts at the centre's lavatories, washhand basins and kitchen sinks, which are connected to vacuum-powered drains that use just one-tenth of the water of conventional drainage systems. The sewage is fed into two rows of 3 m deep concrete tanks within the building, where it is broken down by micro-organisms.

The sewage tanks double as hydroponic beds for plants, including bamboo and willows, that will reach the 4 m high ceiling within a few months, turning the installation into an exotic palm house.

The building itself is a suitably utilitarian – yet elegant – shed, supported on slender steel portal frames. Cladding takes the novel form of inflated double cushions of PTFE membrane, providing insulation, daylight and slightly obscured views of the world outside.

In the surrounding gardens, landscape architect Grant Associates has devised a forest of arresting organic forms. Lofty wigwams in rough fir logs stand by armadillo-like domes covered in green oak trellising, all of which will be swathed in greenery by the end of summer.

In another part of the park, fences, screens and curving sculptures have been created by artist Jim Buchanan and six colleagues out of woven willow stems and branches. As all stems are planted in the ground, this oversized basketwork is already starting to grow green and leafy.

Sustainable construction posed a few problems for management contractor Bovis, particularly when it came to laying the park's maze of paths and tracks. These were designed in compacted Breedon gravel so rainwater would run off into planting beds. As project director Peter Byrne explains: "Usually, a contractor lays drains, gullies and a base layer of blacktop to drain off any rainwater during construction. We weren't able to do that here, so there was a lot of puddling that we had to pump away." The array of eye-catching and mind-jolting spectacles should ensure the Earth Centre fulfils its promise of providing "an exciting day out for the whole family". But, as one local visitor pointed out, its success in one of the most vital areas of sustainability is questionable. The first phase provides employment for only 150 staff, many of whose job descriptions include cavorting as "Earthonauts" with wind-powered hats, energy counters and "Smile-o-meters". Redundant coal miners had hoped for a more substantial job-creation programme from the £42m investment, £35m of which came from the lottery and government coffers.