Solomon built the temple of God, because although his father David wanted to build it, God did not let David do it, but assigned the task to Solomon. Thus this was a building project authorized by God, which means that Solomon was able to finish the work, 

And in the eleventh year, in the month of Bul, which is the eighth month, the house was finished in all its details and according to all its plans. So he was seven years in building it (1 Kings 6.38). 

God wanted Solomon to build this temple. We are even told that Solomon began to build the house of God 480 years after Israel left Egypt. 

Therefore, it does seem significant that it took seven years to build this temple, for as we often see in Scripture, seven represents completion!