Why does Hashem want us to build a Miskan?

 Why does Hashem care about a physical thing?  To teach us that the source of everything is Hashem.  To teach us not to see the physical world as being separate from the spiritual world.  We may be tempted to think that the physical world is unrelated to the spiritual world, but in actuality, the whole world is connected to Hashem.

from a Shiur by Rabbi Kirzner on Aish.com about Parshat Terumah