Turning the world upside down" installation in Kensington Gardens was organised by the Serpentine Gallery, which is to be found in that park.
Each year the Gallery organises an architectural commission for a Pavilion, and this year's design, a wonderfully vivid red construction shown in the photo above, is the work of Jean Nouvel.
A stunning series of buildings have been on the site - as can be seen here. But at the same time as welcoming the creativity there is also a feeling of loss at all that effort (and money) being spent for something that only lasts a few months.
I suppose the answer is to see it while you can in order to maximise its "value" - if so hurry as you only have until this Sunday.