With less than a month to go before Expo 2015 opens in Milan, construction on the fair’s 1.1-million-square-metre exhibition area is still in full swing. With a theme of Feeding the Planet, Energy for Life, the Expo – which will welcome millions to the city from May 1 to October 31 – tackles the big issues around food production and consumption today. One hundred and forty countries will show what their nation is doing to provide “healthy, safe and sufficient food for everyone while respecting the planet and its equilibrium.” It’s an enormous and widespread topic – one that is reflected in the show’s ambitious structures and shelters.

Jacques Herzog, one of the show’s original master planners before he dropped out in 2011, has been openly critical of this very aspect of the event. The group’s vision was to radically reinvent the concept of a world fair, putting the emphasis on content rather than form. Now, he contends that it risks becoming just another “obsolete vanity fair” with large pavilions, each more fantastical than the next. Criticism aside, there indeed will be some grand designs emerging as each country shows off its architectural bravura. Here’s a look at what’s happening on the ground as the site prepares for opening day.

1 The Italian pavilion, by Nemesi & Partners
Expo’s host nation has been preparing to welcome some 20 million visitors, while also erecting its own sustainable pavilion. The white structure is wrapped in a high-tech cladding made of smog-abating concrete panels, from Italcementi‘s i.active Biodynamic line. Rome-based Nemesi & Partners crafted the white, sculptural 13,000-square-metre pavilion, which will envelop the country’s vision of an urban forest behind its expressive woven shell.

2 The Vanke pavilion, by Daniel Libeskind
The highly visible Vanke pavilion by Daniel Libeskind is taking shape, as red pearlescent shingles (created with Italian company Casalgrande Padana) make their way to the top of the wave-like structure. Based on traditional Chinese landscape paintings, the pavilion, which was built for the Chinese real estate giant Vanke, has an interior with just as much movement and flow. Wide staircases lead to a rooftop deck overlooking a nearby lake and the neighbouring Italian pavilion.

3 The Slovenian pavilion, by SoNo Arhitekti
Slovenia’s contribution sees five prisms set on a geometric base shaped to evoke a cultivated field. The mountainous volumes seem almost complete, with warm wooden peaks atop glass and steel. When finished, seating areas and lush grasses will surround the 800-metre-structure, which is meant to reflect the country’s diverse topography.

4 The Chilean pavilion, by Cristián Undurraga
Long and lean, Chile’s suspended wood pavilion will span over 1,900 square metres. Architect Cristián Undurraga tapped into tradition by using timber to great effect, reminding visitors of the role the natural resource plays in the ecosystem. He framed a large wood lintel with a series of crossed beams supported by concrete pillars to create “an intermediate space, a clear horizon” typical of his country’s architecture.

5 The UK pavilion, by Wolfgang Buttress
Nottingham-based artist Wolfgang Buttress heads up the team bringing the UK’s bee-inspired pavilion to fruition. Named the Hive – and somewhat reminiscent of Thomas Heatherwick’s UK Pavilion for Expo Shanghai 2010 – it will welcome guests through a lush meadow of wildflowers that leads to a central sphere based on a honeycomb. The shape draws attention to the importance of bees in food production, and parallels their intricate colonies with human society. Beyond the steel lattice framework, a multimedia installation will fill the space with the buzzing of bees and project a live feed from a real hive against a Corten wall.