Modern readers sometime have trouble with 19th Century writing which uses much more words and description than in modern writing. The writer wants the reader to have the same picture in mind as the author so every detail is mentioned.
The novel starts on January 6th 1482, a normal day, But Hugo describes the events that happened two days before in great detail so it is like looking through a telescope the wrong end at the 1480's.
Here is the link so you can download the book for free:
An easier translation:
We will study this book slowly slowly together.