3. Churches in Kizhi Pogost, Russia
Built only with wood and without nails, can you believe it? This architectural genius was built somewhere in the 17th and 18th centuries. Characteristic of Russian carpentry at the time, no nails were utilised, in fact, they used interlocking wooden joinery. Another unique aspect is the multitude of domes made of diamond-shaped wooden tiles which shine silver under the sun. Who knew that wood could look like metal?