The structure was erected in 1799-1801 by Alexander Tennant, in Simonstown. It was declared a National Monument under old NMC legislation on 31 August 1979.
Blue print of Albertyn Cottage, King George Way, Simonstown. Source: www.digitalcollections.lib.uct.ac.za/
References
https://digitalcollections.lib.uct.ac.za/collection/islandora-22239
Further Reading
https://www.sa-venues.com/things-to-do/westerncape/bysuburb/simons-town/category/craft-and-flea-markets/
https://www.perfecthideaways.co.za/lifestyle/beach/