It's 77 years old, weighs 6 tones and is covered in rust.

But for Heritage Montreal, the Guaranteed Milk Bottle sitting on a vacant building on Lucien-L'Allier just south of Rene Levesque, is a treasure.

"The milk bottle has been in downtown Montreal since the mid-thirties," said Dinu Bumbaru, of Heritage Montreal.

The city has approved zoning for a new water tower for the location where the milk 50-foot bottle currently sits. It used to be the water tower for a dairy.

If the milk bottle is replaced, Bumbaru says heritage Montreal will have two priorities: to fix up the bottle, and to find it a new home.