Contractors Vinci, Taylor Woodrow and Capita have handed over the new £250m Whiston Hospital ahead of schedule after completing one of the most complex construction jobs ever in Knowsley.
The new hospital was built while hospital staff continued to provide health services on the same site.
"This is the largest and most complex project I've been involved in since I joined Knowsley Council many years ago," said Ken King, the authority's building control team leader.
"Our role was to make sure the scheme met all the various building and safety regulations. The sheer scale of this task meant we had to dedicate staff to the project to provide continuity and promote close ties with the developer.
"We were involved in this from the moment initial concept plans came up for discussion and we've had officers onsite since building work began."
The original Whiston Hospital was built in 1843, to provide an "institution and workhouse to house the sick and destitute of the surrounding area".
The original hospital was extended and altered over the years but in 2001 St Helens and Knowsley Teaching Hospitals NHS Trust decided it was time to start again.
The new hospital is six-storeys high and has the floor space equivalent of 15 football pitches. Around half of the construction workers were recruited locally. It has 15 operating theatres and diagnostic facilities. Half of the 800 beds are within single rooms with en suite facilities.
The former accident and emergency block, has been kept but completely refurbished to be used as office accommodation for administrative staff.
King added: "The complexity of the project has stretched everybody involved. We have approved the plans in stages, examining everything in detail.
"It was absolutely essential that the transition from building site to fully functioning hospital was achieved without any glitches. The fact that this has been done is testament to the close cooperation of all the parties involved.
"We have been able to preserve the integrity and intention of the regulations whilst allowing flexibility in design."
The old workhouse, chapel, boiler house and support services buildings were demolished to make way for the new building.
Knowsley's cabinet member for regeneration, economy and skills, Cllr Graham Morgan, said: "This has been a major undertaking for us and our partners and it will give local people the top class health facilities they deserve.
"The fact that this massive scheme has been delivered ahead of schedule is a tribute to the professionalism of our staff here at the Council and all those involved."
Ann Marr, chief executive of the NHS Trust said: "The redevelopment of both Whiston and St Helens hospitals has been the single biggest investment in healthcare in the local community since the start of the NHS.
"These world class hospitals will help us to continue to provide our patients with an excellent standard of care."