Too Large Packages/Subsystems
Packages/Subsystems with a high number of classes/packages indicate that they serve more than one specific responsibility. Splitting them up will lead to a better separation of concerns and especially to better understandability.
Related smells: Insufficient Modularization God Class Large Class The Blob
The following set of tools detects this smell: Designite(for C#) DesigniteJava(for Java)
M. Lippert, S. Roock, “Refactoring in Large Software Projects: Performing Complex Restructurings Successfully”. John Wiley and Sons, 2006.