There isn't a hierarchical representation as such, but types have a /freebase/type_hints/included_types
property which specifies the types which the Freebase web client will automatically include when a type is asserted. You can see these listed in the web client or fetch them with an MQL query.
Important points to note here are that these are hints only: nothing enforces the fact that a /location/citytown
must be a /location/location
, and that it is only the web client which automatically adds the included types - if you are creating topics by any other means, you'll have to add the included types yourself.