Terraced gardens, a landmark building, extensive dedicated cycle paths and a lively town square are all part of plans to reunite Perth and Northbridge by sinking the rail line.

Premier Colin Barnett and planning minister John Day unveiled the final plans for The Link yesterday, revealing the developments planned for newly vacant land above the sunken rail line.

Barnett said the area around the Horseshoe Bridge and above the railway would become an 11,000sqm town square that would add vibrancy and attractiveness to the city.

The area around the town square would include shops, cafes, restaurants and accommodation.

The Link will “revitalise” and “modernise” Perth, the Premier said.

The new town square will be about twice the size of Forrest Place and 25 per cent bigger than Federation Square in Melbourne. For major events, the square will have capacity for between 6,000 and 8,000 people.

“The town square will be the closest point between the Northbridge entertainment district and the Perth city centre and will be a key element in connecting Perth and Northbridge for the first time in 100 years,” Barnett said.

“This area of The Link project will play a central role in integrating Perth’s entertainment, cultural, shopping, employment and public transport areas.”

Day said the town square would complement the proposed underground bus station and Perth railway station and accommodate the dive structures for the Fremantle rail line.

“The plans will see terraced garden areas cover the rail dive structure with grassed embankments and landscaped areas to provide places for people to relax and enjoy,” Day said.

The town square will also include a three-to-four storey feature building that will add to the commercial and retail options for the area.

“The building will help energise the area at night and include ground floor shops and entertainment options for people moving between Northbridge and the city centre,” Day said.

The detailed design for the space will be completed next year, however the town square and central building may incorporate WA landscape elements, as well as significant public art and water and lighting features, to create one of the most significant spaces in Perth.

As well as new commercial and residential opportunities, almost one-third of the entire area will be dedicated to public space such as wide boulevards, alfresco areas, shade and public art.

The first land in the project was released to the market this month and forward works for the undergrounding of the rail line will commence in early 2010.

The project involves sinking the Fremantle rail line from Perth station to Lake Street, undergrounding the Wellington Street Bus Station and creating several important connection points between the city centre and Northbridge.

EPRA’s lead consultants are Taylor Burrell Barnett and Jones Coulter Young Architects.