NVA has concluded missives with the Catholic Church for St Peter's Seminary in Cardross, Argyll and Bute.
The A-listed building was designed and built in the 1960s as a training college for priests but it has not been used since the 1980s and is now a ruin.
NVA aims to restore part of the seminary and use it as an art space.
Its plan would stabilise the structure and gradually restore some interior spaces for cultural and educational use.
The charity has already received £100,000 from Creative Scotland's National Lottery Fund towards the project.
It still needs to raise £2m by 2013 to take its proposals forward.
St Peter's Seminary was designed by Glasgow architects Gillespie, Kidd and Coia.
The Roman Catholic seminary, which belonged to the Archdiocese of Glasgow, was completed and consecrated in 1966.
The distinctive zig-zag design and concrete appearance soon brought architectural recognition to the site.
However, as numbers entering the religious life fell and with high maintenance costs, the decision was taken to close the college.
In 1980 the seminary was deconsecrated and fell into a state of disrepair.
The building was Category A listed by Historic Scotland in 1992.
The World Monuments Fund, which works to preserve endangered cultural landmarks, added St Peter's College to its register in June 2007.

Three West Mercia Police officers had now been interviewed under criminal caution, the Independent Police Complaints Commission (IPCC) said.
Mr Atkinson died after contact with police in Meadow Close, Trench, Telford, on 15 August last year.
West Mercia Police said it continued to co-operate with the IPCC.
The three officers had been served with gross misconduct notices, the police watchdog said.
IPCC Commissioner Derrick Campbell said: "At the conclusion of our independent investigation I will consider whether to refer our investigation report to the Crown Prosecution Service to make a decision on any potential charges against police officers.
"A criminal investigation does not mean that criminal charges will necessarily follow."
Mr Campbell said its independent report would consider whether any officers should, in the watchdog's view, face misconduct proceedings.
Investigative inquiries had ended, but the IPCC investigation report could not be finalised "until the full pathology and toxicology reports are provided", the watchdog said.
It said IPCC investigators had spoken to about 15 other police officers as witnesses, along with more than 15 members of the public and paramedics.
Forensic experts had also been consulted.
A Taser used during the incident had been analysed and investigators had "transcribed relevant police Airwave radio transmissions and examined police policies on the use of force".
West Mercia Police Assistant Chief Constable Martin Evans said the force's "thoughts and sympathies" were with Mr Atkinson's family and friends and it continued to co-operate with the IPCC throughout its investigation.
He said: "It would not be appropriate for us to comment further at this time while that investigation is ongoing."
Mr Atkinson started his career at Ipswich Town before moving to Sheffield Wednesday, Real Sociedad, Villa and FenerbahÃ§e
A public arts charity aims to raise £10m over the next two years to help save a building considered one of Scotland's great modernist structures.
[NEXT_CONCEPT]
A third police officer has been investigated over the death of ex-Aston Villa star Dalian Atkinson who was shot with a Taser, it has emerged.