An aerial impression of the proposed new $50 million Science Alive! complex at the Durham Street law courts.

A new $50 million international science centre will be developed on central Christchurch's Durham St law courts site.

Not-for-profit science and technology centre Science Alive! announced today it would be buying the property and buildings from Ngai Tahu Property and planned to develop the site once its existing occupants, the Ministry of Justice, move to the Government's new justice precinct in late 2017.

Exhibition space at the new 5500 square metre centre would be double that of its former Moorhouse Avenue base, which was demolished following the earthquakes.

SUPPLIED An architect’s impression of the view from Victoria Square of the proposed new Science Alive! centre.

Science Alive! chief executive Neville Petrie said after five years without a centre, it was exciting to have a building secured, but there was still a lot of work to do to create the facility.

The centre would include a 100-seat, full dome 3D theatre, which would also be used as a planetarium. It would have a quake gallery with a realistic simulation of the Canterbury quakes and also feature entertainment-orientated interactive activities. The new venture planned to attract more adults and would open in the evenings.

It was expected the first stage, including the dome theatre, would open in early 2018 and other stages later that year depending on funding.

Almost all the buildings within the courts precinct, which borders Chester St West, Armagh and Durham Sts, would be adapted, re-purposed, and re-strengthened further, including the historic Family Court building fronting Armagh St.

However, the science centre would not encompass all the buildings in the complex, with about 7100 square metres of space being leased out for commercial purposes, including space in and around the tower that houses court rooms and judges' chambers.

Science Alive! Charitable Trust Board chairman Professor Philip Butler said tenants have already shown an interest in the site including a childcare centre, medical facilities and retail and hospitality operators.

The trust board already has $40 million from its reserves, insurance proceeds and a bank loan to contribute to the project and wanted to raise another $10m.

Butler said there were people prepared to support a charity like Science Alive! that had such a focus on "betterment of the community".

"The interest in public science has never been stronger and Christchurch will now have its own dedicated centre incorporating the much-loved Science Alive! brand that many people grew up with."

Butler said the centre would provide New Zealand's scientists with a dedicated public area to showcase their research and initiatives.

Science Alive! has been without an exhibition space since the quakes forcing it to change its focus in order to survive. It developed an extensive outreach programme in schools and used other sites across the city to hold activities and exhibitions. It also designed and developed exhibits for science centres in other countries.

Christchurch Mayor Lianne Dalziel said the new centre would contribute to tourism and add to the "international attractiveness" of the city.

"Cities around the world are recognising that science centres not only attract tourists, they also ignite a passion for science in the children who will be our future city leaders."

The board started doing due diligence on the site more than a year ago after approaching Ngai Tahu Property about purchasing it.

Ngai Tahu Property chief executive David Kennedy said the company was thrilled the legacy of such an iconic set of buildings would be the advancement of New Zealand's innovative science and technology spirit.

The buildings within the complex stretch four architectural styles, including 19th century gothic and the 1970-1990s chambers.

A team of architects led by Pete Bossley and Cymon Allfrey were working on the project. Bossley designed Te Papa Museum in Wellington and worked on the Auckland War Museum and the Voyager New Zealand Maritime Museum.