If you are intending to carry out research on an Aboriginal and Macassan archaeological place, go to Indigenous Heritage.
There is also a separate section on Maritime Heritage.
If you have a more general interest in researching the history of a place in the Northern Territory, this section provides further information.
Many places on the NT Heritage Register have either related Factsheets or more extensive Background Historical Information, authored by the Heritage Branch. When you search for a place on the Register, you can find these (if they exist for the place in question) under 'Further Information'.
There are many other sources of information on line, including the following: