A detailed description (as much as it could be) about Christianism - from Jesus' days till our days.
Very good investigation from many different sources, shows the route of Christ's Way through the ages.
Of course it's hard to know the whole story - since the Bible is not a historical but a spiritual book & since there are not many written reports from the original church - but we can see "small pieces" in various testimonies of what Jesus left behind.
The fact is, that no one knows how God is working. We can see that He still has His people on this earth - working in the same way that the first apostles did - but we don't know exactly the past as we don't know the future.
We know only what we need to, for our salvation.