Designed by Adilberto Libera in 1937, on the crest of a peninsula in Capri (more here). The legend has it that Curzio Malaparte, the client with a lively if at times questionable politics, didn't like the architect's design and that he build it himself with Adolfo Amitrano, a local stone mason. It is difficult however to imagine a non architect coming out with such a bold and challenging - especially at the time - design. You can see plans and sections here.
It is most famous for its roof that forms a giant staircase leading to a platform that seem surrounded by the sea. It is particularly successful as otherwise the design couldn't be simpler from the outside, it is a simple box in red render with windows and a flat roof (as is not unusual in this part of the world). In other words the success comes from a simple shape that allows you to comfortably walk on the roof. The detailing is straightforward, almost traditional. The concept demonstrates that a powerful informal idea can be hugely powerful when done simply.
The other groundbreaking aspect of the design are the windows which are framed like paintings on the wall of the sea scape beyond. This is the only out of the ordinary detail as within the outer - painting - like surround no frame interrupts the view that thus looks like a giant postcard. As far as I know, this is one of the first example of a picture window; there had been glass walls before, some house by Mies van Den Rohe in Germany for example - but these are not adapted to such hot climates as they overheat. The window as a picture gives the same powerful connection to the outside but with a limited heat gain (or loss). In this way, it is a great example for our times where we need to reduce glazing to avoid wasting energy.
The best way to see it - as it is usually closed - is to watch Jean Luc Godard's film Le Mépris starring Brigitte Bardot & Michel Piccoli.
More views of the inside on Andrea Jemolo website.