The idea that there are eras in architecture is an incredibly destructive Progressive idea. Traditionally all architecture was a continuation of ideas and materials, an accumulation of human experience, ingenuity, beauty. The only ones breaking this chain were the modernists.
Even materially, there are no eras. Technically speaking we are still living in the "Stone Age": we are using millions of times more stone per capita today than we ever did during the stone age. We are still building with wood, mud, straw, iron, but we keep adding new materials. 
A picture speaks more than a thousand words they say. Well here is the picture that explains the 20th and 21st centuries, architecturally. (ht:@Arch_Revival_)
@Arch_Revival_ Every now and then we come up with new materials. It mightn't be the best or even sustainable, sometimes it is just the material whose manufacturer has best managed to capture the market (often through manipulation of regulations). Will the materials of today be around in 2118?
@Arch_Revival_ Some materials are lost to us because we forgot how to make them: roman concrete, or Coade Stone for example. Others because we found they were bad for us, like asbestos.
