Simplicity is the ultimate luxury. 
         — Leonardo Da Vinci.

Funny thing about that. It can be exceedingly difficult to make something simple. It's really more accurate to say 'appear' simple, because in architecture we are manipulating multiple elements to achieve a specified function within a desired aesthetic.

For me the architectural aesthetic is not just how a building looks but rather how seamlessly it integrates and balances function, construction and appearance together with the least possible compromise to each.