Being asked by the Pharisees when the kingdom of God was coming, he answered them, "The kingdom of God is not coming with signs to be observed; nor will they say, 'Lo, here it is!' or 'There!' for behold, the kingdom of God is in the midst of you." Luke 17:20–21 (RSV)
The Pharisees were correct in seeking the Kingdom of God. They longed for its coming, and for that purpose, they were zealous for the Law. It was believed that if a mere ten kept the Law perfectly, the Messiah would come. They had not succeeded yet, but they kept their vigil.
Their zeal blinded them to the fulfillment of the very promise they sought. The Messiah they sought, the kingdom of God they prayed would come, was right in front of them. God's kingdom is not a place. The kingdom is Jesus.
The Pharisees' mistake is one we often make as well. We are looking for a place, a kingdom when the promise of God is we will be in Him and He in us. If we content ourselves with heaven, we miss the One who is our life and salvation.
Jesus is the way, the truth, and the life. He brings us to the Father. Our eternity is to live in the love of the Holy Trinity. We speak of a place, for our words are not adequate to describe the joy that is to be ours. Words may fail us now, but our praises will be sung in the kingdom.