Green charity Greenpeace has launched a Battle of the Architects design competition to create a fortress-like structure in a bid to block the construction of a third runway at Heathrow Airport in the UK.

The structure is expected to be built in the centre of a one-acre site where the airport operator BAA intends to construct a $12.7bn runway and sixth terminal.

The structure is a peaceful protest by the group and will support owners of the land, local residents and seasoned campaigners.

Australia’s activist-architect Andrew Maynard may sign up for the competition. However, larger firms such as Norman Foster Architects chose not to enter the competition.

The proposed land is owned by Greenpeace, which distributed its ownership to 60,000 people across the world.

Grimshaw is designing the master plan for the expansion and the new runway.

The competition’s brief is unique and is hailed to become iconic once completed.

The contest is open to architects, architectural students and architect-led mixed disciplinary teams of engineers, artists, landscape designers, sculptors and other professionals aligned with associated bodies as well as the public to collaborate and submit designs.