Field History Tracking is a very useful tool to use on an object. This is especially great if you have many users updating the same record and you want/need to know who, when they made they made, what changes they made. The result of enabling Field History Tracking is a related list on the object that shows this information.
But only in the Salesforce Classic.
In the Lightning Experience the Field History Tracking related list is not available. Why? No really certain. You figured this would be available in the early Lightning Experience considering how much this is a highly used and such a classic functionality of Salesforce. For some reason it is not and it will not be available until Spring 17 or Summer 17.
The work-around is that you can create a report of this information. Sure it would be great to just see this information on the object instead of going to reports but it’s better than nothing, right?
To read more about this on Salesforce: Click Here