Landscape With Regards to Site

We try as architects in general to build into the context of the site. However, this decision on the way we will build on the site is a difficult task. What makes a building site specific? We looked at buildings like Falling Water and the Farnsworth house, both are considered masterpieces, but deal with their sites in very different ways. What makes these two houses successful? Is it the designer or the care with which the building and site coexist?

Weathering

Seems like a fairly basic concept, buildings age and deteriorate overtime, so what and how can we as future architects do about this? Should we consider the buildings we design to last for the next century or more, or do we consider that as we build something the end is already in sight?

Proportions ands Systems

We have talked about how the world is seen from different perspectives and that many believe that their is a proportional system that dominates the natural forms around us. Do you agree with this? Is this just an attempt to explain what we really don't understand, and are people deciding that proportions go beyond symmetry and try to blur the lines between proportion and cause and effect?