Here is the main hall of Rinnoji Temple. It's the largest wooden building in eastern Japan. A large steel building has been erected around it and it has been completely disassembled for repair/restoration. As you will see, no nails were used in its construction. Rather, all the beams and posts are slotted and have pegs carved into them so that the whole thing is fitted together. Do you remember "Lincoln Logs" from your childhood? This is Lincoln Logs on steroids. ;-)
While I was living in Japan, I saw a new construction using the same techniques. Men with large wooden hammers were driving one slotted beam into the slots in the beams beneath.
A visit to Nikko, Japan