They look like tombstones and you wonder what kind of graveyard this is. They're actually "magnetic" termite mounds and you find them in Litchfield National Park in the Northern Territory, near the town of Batchelor, 100 kilometres southwest of Darwin.
The termite mounds rise to as much as three metres in height, look relatively flat — and they all face the same way with their thinner edges facing north and south. The thin ends are thus on a north-south axis, giving rise to the term "magnetic."