GetFoldersize is a free and useful application that can list details of all the folders and subfolders present in Windows. It makes it easy to see how the disk space is used for these folders making it simpler to manage it. This is done by listing all the available folders, the sub folders in them along with the files present.
Download it from here. There is a portable version available too if needed.
Simply run it and then select the drive partition whose folder structure needs to be seen along with various options like whether display size should be in B, KB, MB and so on plus whether to expand all the folders and so on. Overall, the default settings are quite easy to read and give a lot of information regarding the entire folder structure.
This is a very useful application if you often experience low disk space too often or not really knowing what is taking up all the space.