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."

Alderney to get a Royal Visit on 15 December
Two airlines bid to operate Guernsey's essential air links
Guernsey overtakes Jersey as top Channel Island for UK Sea Travel
Agency staff to cover ambulance services in Alderney over Christmas
Guernsey venues highlight support training with window stickers
Spare rooms sought to help tackle homelessness in Guernsey
One of Britain’s rarest fungi has been found on Alderney
Channel Islands' parliamentary Standards Commissioner resigns