Second Chronicles 3:9 tells us that there were nails made of gold which were used in the construction of the temple. Golden nails, really? Seems like that wouldn't be very practical either functionally or financially, but isn't that the point? Solomon wasn't trying to be practical; he was shooting for extravagant.
Before we get into that though, notice in verse 1 that Moriah was the site of the temple. Moriah had been the location of Abraham's sacrifice of Isaac (Genesis 22:2) and supposedly of Jacob's vision of a ladder reaching into heaven (Genesis 28:10 - 17). Also, as we have seen before, it was the place where the angel of death stopped in his execution of Israelites just before David came and offered a sacrifice to God there... back when it was Oman's property. It was a piece of real estate that was destined for eternal significance. Today, the Dome of the Rock is there. Someday, Jesus Himself will be rightfully worshipped there, in His exalted glory, during His millennial reign.
So, with such a special place in God's program, both past and future, it is perfectly understandable that David, Solomon and Israel would spare no expense in building a palace for God there. And what a place it must have been. It's size; it's geometric simplicity and majesty; the wide use of gold to overlay the construction materials (and in some cases to do the constructing itself), the artistic splendor of the ornate decorations and engravings all over it and most particularly the jewels which were used to garnish the surfaces of gold... all these things together (and more) worked together to make an architectural wonder of immeasurable value in its day.