If there's one word that sums up our most popular projects of 2015, it's "diversity." The list features architects ranging from old favorites such as SANAA, Diller Scofidio + Renfro and OMA down to newer names like Sculp[IT] and Tropical Space; it also includes everything from museums to multi-family housing and spa retreats to chapels - along with the usual smattering of private residences. Interestingly, this year's list also shows the symbiosis between great architecture and great photography, with no less than 4 projects also appearing in our most bookmarked images from this year's World Photo Day. But despite their diversity, there's one thing all of these 20 projects have in common: great architecture. So settle in, relax and read on - here's our 20 most popular projects of 2015.

For many centuries, the demands of gravity appeared to give architecture one requirement that was largely unquestionable: that structures must rise vertically. However, with the advent of steel it was revealed that this limit had not been provided by gravity but by our own limited technologies. In this text, originally published by Domus Magazine in Italian and shared with ArchDaily by the author, Alberto Campo Baeza reflects on the architectural freedom offered by steel structures and the arbitrariness they bring to architectural space.

Isaac Newton was resting under an apple-tree in his garden when an apple fell on his head. Being endowed with such a privileged head and thoughts faster than lightning, he rose forthwith from his afternoon nap and set about calculating the acceleration of gravity.

Had Sir Isaac Newton had a little more patience and had he taken his time in getting to his feet, he might have noticed how, following the apple, a few leaves also fell from that same apple-tree, and while they fell, they did so in quite a different manner to the apple.

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