Jan Harmsgat is a country house on the outskirts of Swellendam. The house was originally slave quarters. Lady Anne Barnard stayed there and wrote in her diary about Jan Harman’s schat (treasure). Johannes Harman Jansz Potgieter was born.in 1674 on a farm near the Langeberg Mountains. He was married in 1714, and the farm appears on the grant of 1723 as Jan Harmansz Schat (treasure). He was gored to death by a buffalo and later found in an aardvark hole.
In 1731 the grazing rights were granted to Jacobus Botha, a well-known hunter whose career was brought to an end a few years later, when he shot a lion, and the lioness (which he had not seen) attacked and mauled him. He recovered but was not able to hunt again, and in 1734 Governor de la Fontaine made a freehold grant to him, for services rendered, of the farm Jan Harmans Gat which he was then occupying. The farm was described as "vier uur te perd van die dorp Swellendam". Botha lived to the age of 90, dying in 1782, and his 12 sons gave him 190 grandchildren.
In 1789 the farm was owned by Hermanus Steyn de Jonge. In 1765 he married the widow Margaretha van Staden. In addition to farming, he also sat on the District Council of Swellendam. In 1795 the farmers rebelled against the Dutch and declared themselves independent of the Cape Government. Hermanus Steyn was chosen as the president of the new Republic of Swellendam, which lasted for 3 months before the British assumed control of the Cape Colony. He is buried on the farm in a small plot marked by a granite gravestone.
F.J.van Eeden, a member of the Legislature and grandson of Gideon van Zyl, inherited the farm and changed the name to Nooitgedacht. One day, while in a Legislature meetig, he became so angry about a proposed excise duty, that he had all the vineyards cut down, and planted orange trees in their place. Four giant old orange trees which had been planted by Hermanus Steyn, produced wagon loads of oranges for 150 years, but were then cut down by van Eeden, and 5 dozen orangewood chairs made from the timber.
In 1988, Judi Rebstein (maiden name van Eeden) came across the dilapidated farm and recognised it from old photographs as the farm once owned by her great-great-grandmother. After working in theatre and film production, Judi settled at Jan Harmsgat with her husband Brin. They restored the old slave quarters and the old wine cellar. The wine cellar contains the old wine tank where Hermanus Steyn once made wine enjoyed by the Swellendam rebels.