Some of architecture's biggest names are vying to lead a new mixed-use skyscraper development on a prominent site in Melbourne, Australia. From twisting greenery-covered towers to an "illuminated cloud," the six designs for Southbank by Beulah show the firms letting their imaginations run wild. Furthermore, most of the designs show towers that would become Australia's new tallest skyscraper if built.

Local developer Beulah International purchased the prominent 6,061 sq m (65,240 sq ft) Southbank plot currently taken up by a BMW dealership late last year. The project will have a total budget of AUD 2 billion (around US$1.47 billion).

Several of the architecture firms involved will likely be familiar to regular New Atlas readers, including MAD, UNStudio, BIG, Coop Himmelb(l)au, OMA, and MVRDV. The projects range in size, however all but one is confirmed taller than Australia's – and the entire southern hemisphere's – tallest tower, the Q1, in Queensland (the height of one of the designs hasn't yet been revealed).

Below, we briefly cover each design, but head to the gallery to see more on each. We'll also be back with the winner when it's unveiled, which is expected to be sometime this month.

Urban Tree - MAD Architects and Elenberg Fraser

MAD and Elenberg Fraser's nature-infused Urban Tree skyscraper would rise to a total of 360 m (1,181 ft)-tall and provide pedestrian access to a "mountain village" (a familiar theme for MAD) that includes a playground, artwork, and a water feature. Elsewhere in the tower would be residential and office space. It would be topped by a novel platform called "The Cloud" that would house the hotel's public amenities and change appearance with LEDs.

Green Spine - UNStudio and Cox Architecture

The Green Spine, by UNStudio and Cox Architecture, envisions two twisting glass towers that are defined by their greenery-covered terraces. The taller residential tower, which would reach 356.2 m (1,168 ft), would offer pedestrian access to a public Botanic Garden at its top, while the smaller tower would reach a height of 252.2 m (827 ft) and host office and hotel space.

The Lanescraper - Bjarke Ingels Group and Fender Katsalidis Architects

Taking the form of a pile of stacked glazed blocks, Lanescraper from BIG and Fender Katsalidis Architects would include an auditorium with a capacity of over 3,000, as well as a BMW experience center that takes up four levels, and is connected by a central void and car lift. The building would reach 359.6 m (1,179 ft), and also host retail and cultural amenities, such as a library, cafes, and restaurants. Elsewhere in the building would be office space, hotel rooms, and residential units.

The Beulah Propeller City - Coop Himmelb(l)au and Architectus

The Beulah Propeller City, by Coop Himmelb(l)au and Architectus, would consist of four main parts: a public podium, office space, hotel space, and apartments. The tower would reach a height of 335 m (1,100 ft), and be topped by a penthouse. This plush pad would offer a private garden and pool, as well as fantastic views of Melbourne.

Stack - MVRDV and Woods Bagot

MVRDV and Woods Bagot's Stack would, well, stack large interconnected spaces including parks, retail facilities, residential areas, hotels and something called an "underwater city window," to create a well-connected vertical city. The building would rise to 359 m (1,177 ft) and be topped by a rainforest-style garden. Each section would have its own appearance from outside and lend the building a distinctive patterned look.

Unnamed project - OMA and Conrad Gargett

This colorful project, by OMA and Conrad Gargett, emphasizes its base, which would host a ground-floor market inspired by local historic arcades and vaulted markets. The base would also feature cultural, commercial, educational and social elements, with retail and dining areas. The upper parts of the tower would be dedicated to office spaces, a hotel, and residences – the latter situated at the top to maximize views and daylight. As well as lacking a name, its height has also not been revealed.

Update August 6, 2018: The height of the OMA design has been given as 345 m (1,132 ft), meaning that whichever Southbank by Beulah tower design is chosen, the building would become Australia's tallest skyscraper.

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