Laura Cumming’s best art of 2017

There was revolutionary fervour from Russia, dazzling critiques of the American dream, and unforgettable faces…

• Observer critics’ reviews of the year in full

Everything you wanted to know about bitcoin but were afraid to ask

The value of cryptocurrencies is rising fast. But is it sustainable? And how does it work, anyway? These questions, and many more, answered…

Is Richard Branson’s high-speed train in a pneumatic tube pie in the sky?

First airlines, then spaceships. Now the Virgin boss wants to build Hyperloop One – a high-speed, pneumatic maglev railway. But engineering experts doubt that it will ever leave the station

The Bilbao effect: how Frank Gehry’s Guggenheim started a global craze

Opened 20 years ago this month, the glittering titanium museum had a wow factor that cities around the globe were soon clamouring to copy

The Spanish holiday home as an architectural collectible

In rural Aragon, the Solo Houses project is giving international architects free rein to create the buildings of their imagination