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.
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.