The government has pledged billions for hospital projects across England, at the start of the Conservative party conference.
The plans include a £2.7bn investment for six hospitals over five years.
A new approach to NHS mental health treatment will also be trialled in 12 areas of England - with housing and job support alongside psychological help.
NHS Providers welcomed the funding but said more was needed to make up for "a decade of capital squeeze".
The organisation, which represents trusts in England, said the NHS's annual capital spending of around £6bn needed to double over the next five to 10 years to meet its needs.
The government says £70m is also being invested in the mental health pilot areas, with the NHS building more ties with charities and local councils.
About 1,000 extra specialist staff will be recruited in 12 pilot sites, with expertise in a range of mental health issues, the government says.
Under plans drawn up by Health Secretary Matt Hancock, the government has said £13bn will be spent on hospital projects, including entirely new buildings or revamping existing structures to improve facilities.
The same pot of money will also be used to develop plans for further projects in the future.
Mr Hancock said the funding would come from taxpayers, rather than PFI contracts whereby private firms fund the cost of building facilities and, in return, the state makes payments over a stipulated period of time for their use and management.
The six hospital trusts to benefit from the £2.7bn in funding are:
- Whipps Cross Hospital, in Leytonstone, east London
- Epsom and St Helier Trust
- West Hertfordshire Trust
- Princess Alexandra Hospital Trust
- University Hospitals of Leicester Trust
- Leeds Teaching Hospitals Trust.
Mr Hancock told Sky News's Sophy Ridge on Sunday programme that funding for these six trusts was in place so building work could begin "straight away".
A further 34 hospitals will receive £100m in initial funding to start developing projects, including Addenbrookes Hospital in Cambridge, the Queen's Medical Centre in Nottingham and the North Manchester General Hospital.
The remaining projects, including up to a dozen smaller community hospitals in Dorset, would be completed over the second half of the next decade.
The plans also include £200m for replacing MRI, CT scanners and breast cancer screening equipment.
The government has certainly tried to grab the headlines with its claim that 40 new hospitals are to be built in England. But the announcement is very scant on detail.
While we know which places these new hospitals will be built in, we don't know the scale of the plans.
For example, when the government announced 20 projects in the summer it turned out that some amounted to little more than re-development of wards and clinics in the community.
The green light has been given to six schemes - and with £2.7bn of funding attached we can assume they will be pretty substantial.
But it's far from certain that will be the case for the other 34.
The government has basically given health bosses the go-ahead to draw up plans, not to actually build them. The money being talked about to pay for them in the long-term suggests some may be on a smaller-scale.
The final - and perhaps most important - element to be decided is just how much the budget for buildings is to be increased by in the coming years to pay for all this.
Around £7bn is being spent this year, but there is already a huge backlog of repairs and maintenance that needs to be done.
If ministers are serious about these new buildings and tackling that, the budget will have to increase substantially.
NHS Providers chief executive Chris Hopson said the commitments were "significant" and "particularly good news" for the six hospitals that would directly benefit.
However, he said funding to complete schemes in 34 other hospitals had not yet been allocated.
"It's not just these six hospitals who have crumbling, outdated, infrastructure - community and mental health trusts, ambulance services and other hospitals across the country have equally pressing needs," he added.
Labour's shadow health secretary Jonathan Ashworth said the government's announcement that it was building 40 new hospitals had "quickly unravelled as spin".
"This isn't 40 new hospitals, it is just reconfiguring six," he said.
"New investment is desperately needed and of course we welcome any genuine new money, but patients and demoralised NHS staff are fed up of being taken for fools like this."
The government said there would be an extra £2.3bn a year by 2023-4 to improve mental health care and £975m of funding was earmarked to provide community mental health provision.
The 2.3bn figure was announced when the government outlined its future priorities for the NHS in January under the NHS Long Term Plan. The 12 pilot areas will be funded from this pot.
Mental health minister Nadine Dorries said the plans for a new approach to mental health treatment and £70m of investment in pilot areas would begin a "step-change" in provision.
The pilot areas will cover services in the Humber, Coast and Vale Health and Care Partnership, Frimley Health and Care, and Surrey Heartlands; providers for Cambridge and Peterborough; Hertfordshire and West Essex; north-west London; north-east London; Herefordshire and Worcestershire; Lincolnshire; South Yorkshire and Bassetlaw; Cheshire and Merseyside, and Somerset.
Ministers say the plans will involve a range of mental health issues, including eating disorders and alcohol addiction, psychosis and bipolar disorder.
Speaking ahead of the start of the Conservative Party Conference in Manchester, Ms Dorries added: "We know there are many causes behind mental illness - including significant life changes, problems at work or addiction - so it is only right that the NHS brings services together to serve patients in their communities."
'Discovered and made in Britain'
Meanwhile, the prime minister has unveiled a £200m cash injection for the UK's health and life sciences industry. The funding will be matched by £400m of private investment to allow science companies to expand development plans.
This government hopes the investment will allow companies to raise capital to run clinical trials, employ more industrial scientists and boost manufacturing in the UK.
Boris Johnson said it was part of his vision to have a "vibrant post-Brexit economy fuelled by science and technology".
He said: "The UK has the best universities in the world and we have a proud history of scientific discovery from penicillin to sequencing the human genome. But too often we let another country commercialise this discovery.
"I want the lifesaving cancer treatments of tomorrow to say 'discovered and made in Britain'. That means allowing enough late stage capital to be mobilised so that these science discoveries do not have to go overseas to be commercialised."