The Limes at St James' Hospital in Milton will provide care for elderly patients when the 36-bed unit opens next year.

The £8m centre will be built by Kier Southern on an area to the east of the site.

It's called The Limes because of a mature lime tree that will be a focal point.

The foundation stone was laid on Friday by Portsmouth City Primary Care Trust's chairman Richard Hibbert and consultant psychiatrist Dr Carol Trotter.

Judy Hillier, director of clinical and community services for the trust, said: 'The event was wonderful.

There was a huge number of people from the units that will be transferred to The Limes. The sun was shining and it was a really positive opening.

'Dr Trotter gave a very emotional speech on how she will be so pleased to see the unit open.

'It will be one of the best units in the country for providing care for people with mental health problems.'

The unit's two wards will feature separate male and female sleeping accommodation with a central shared day space.

Seating areas at intervals provide places for patients to rest along the corridors and at the end, where there will be fantastic views out to the landscaped gardens.

Each ward has its own secure garden for patient recreation, and a central therapy garden will enable patients to carry out therapeutic tasks under the supervision of an occupational therapist.

The single-storey unit means that plenty of natural light will filter through the large windows, enabling patients to see out into the gardens even from their beds or when sitting down.

The unit should be open in 12 to 18 months.