I've heard a lot of ideas about that over the years. But it wasn't until I slowed down and listened carefully to Paul's prayer for the Ephesian church that I saw something I'd never seen before. Paul prayed, among other things, that they would know:
Where are the riches of Christ? Where is His glorious inheritance?
That's me and you. We Christians are his riches. We, the church, are his inheritance, his treasure.
Where do we go to experience the fullness of Christ?