The mausoleum is built from a plain ashlar sandstone. It is a gable-ended structure with a sloping stone-slabbed roof. Each gable end is topped with a stone finial. The mausoleum is small (4m x 6m) and is surrounded by a circular grassed area, which is enclosed by a low stone wall set with two wrought-iron gates.

Because of the strong historical connection between Macquarie and Australia, the site has international significance. Macquarie is now seen as one of the more enlightened of the early governors and is an interesting and significant historical figure. In April 1809, Macquarie was appointed Governor of New South Wales to replace the notorious William Bligh, whose governorship had been wracked with controversy. He took up his commission as governor on 1 January 1810. The pressures of a commission of inquiry into the state of the colony resulted in his resignation at the end of 1820, and Macquarie returned home to his estate on Mull to defend the charges made against his administration. He died in 1824 during a visit to London.

The mausoleum was probably erected over the Macquarie family burial plot around 1851 or 1852 by the Drummonds of Strathallan, who had inherited the Gruline estate. At this time, the two existing memorial stones – Macquarie’s in red Peterhead granite (commissioned by his wife) and his wife and children’s in white marble – were fixed to the exterior of the mausoleum on the south-eastern and north-western walls respectively.

In 1948, the mausoleum was gifted by the then-owner of the estate, Lady Yarborough, to the people of New South Wales through an Australian trust. A committee of the National Trust of Australia (New South Wales) was subsequently formed to take ownership of the property and to administer the remaining funds. Since 1971, the National Trust for Scotland has worked in cooperation with the National Trust of Australia (New South Wales) to care for the property.