Something big is happening outside Optus Stadium, with a giant screen emerging next to the Swan River.

It's part of a new amphitheatre project designed to liven up the area with more live sport, community activities and an outdoor cinema.

It's been going up between Optus Stadium and the Swan River for the past few weeks and sits in front of a 1000-person amphitheatre.

It is smaller than the screens inside the stadium, but at nine metres by 16 metres it's bigger than those in the Northbridge Piazza and even Fed Square in Melbourne.

The State Government contract says the cost is a little over $670,000.

The full calendar of what will be shown on the screen hasn't been locked in yet, but it will definitely be for more than just the footy.

Testing will start this week. An opening date is still being worked out.