A dense white grid made up of 27,000 elements has just gone up in London¡¯s Kensington Gardens: It¡¯s the Serpentine Gallery¡¯s 2013 summer pavilion, designed by Japanese architect Sou Fujimoto.

The pavilion originated in 2000 to host the gallery¡¯s annual fundraising party, talks and daytime visitors over a three-month period. Previous designers include Pritzker Prize winners Zaha Hadid (2000), Rem Koolhaas (2006), Frank Gehry (2008), Jean Nouvel (2010) and Peter Zumthor (2011).

At 41, the Tokyo-based Fujimoto is the youngest chosen.

¡°This has been a dream,¡± Fujimoto said in an interview at the media preview. ¡°The pavilion has a beautiful history.¡±

Describing his forerunners as ¡°heroes,¡± he remembered being intrigued in 2002 by Toyo Ito¡¯s pavilion design. ¡°It was my younger days,¡± he said, ¡°and it was a big inspiration to me.¡±

Fujimoto¡¯s pavilion is a forest of connected white tubes. From up close, it looks like an elaborate climbing frame. Farther away, its jagged, busy exterior recalls a Gothic cathedral facade.

Inside, the pavilion is airy and light, with stacked-up glass blocks that can be used as bleachers. Roofing is provided by see-through polycarbonate discs that cover each grid and allow the rain to cascade away.

¡°I tried to create something like nature, but by artificial methods,¡± said the architect, wearing frameless glasses and a black linen suit. ¡°The whole shape is rather organic, like a cloud. At the same time, the whole thing is made by really sharp industrial materials.¡±

Serpentine Director Julia Peyton-Jones said Fujimoto was picked because he¡¯s ¡°driven by this idea of nature and architecture,¡± and because a pavilion designer cannot have built in England ¡ª ¡°so that rules out a whole lot of architects immediately.¡±

Not all the chosen architects had Pritzkers, she said; Ito, picked in 2002, only won the Pritzker this year.

¡°The brief is unbelievably simple: It¡¯s the same every year,¡± said Peyton-Jones. ¡°We give them an opportunity where they don¡¯t have to worry about bathrooms, they don¡¯t have to design the kitchens, there are no walls.¡±

¡°We really want them to expand their practice,¡± she said. The pavilion can¡¯t take more than six months to complete, and has to be built with funds the gallery raises.