A mechanical digger has begun tearing down the old St Peter Port School.
The Les Ozouets campus was built in the 1960s.
Specialist contractors have been removing asbestos, and now a mechanical digger is being used to break the building down.
The site should be levelled by mid-August, to allow a new Guernsey Institute to be constructed.
Institute Head Tracey McClean says the new campus will offer opportunity to many post 16 students:
"In three years time hopefully we will be moving into a brand-new building, so it will mean that we can increase our provision and opportunities on the island.
There's nothing like learning in the classroom and being with a group of peers and sharing ideas."

Gas price increase for Guernsey and Jersey
Islanders asked to take action to protect Guernsey's biodiversity
Aurigny sets out timeline for its Alderney services
New restaurant and flats planned for Guernsey waterside location
Full-fat milk gaining popularity in Guernsey
Guernsey cannabis debate to be postponed
Guernsey’s Wildlife Hospital build reaches the halfway point
Channel Islands Contemporary Art Show opens