Hammersta castle was a 13x18m wide two-storey stone building built around the year 1300 by Eringilse Nilsson, who's father was married to a sister of Bridget of Sweden. Eringilse's son (with the same name), was married to a Danish woman, Brita Olofsdotter Tott, and when the situation between Sweden and Denmark became tense around 1450, Tott was sentenced to death for spying for the Danes. Luckily for Brita she was pardoned and later paid for the famous fresco paintings that you can now see at the Ösmo Church.
The castle was abandoned in the 15th century. Between 1628 and 1767 the estate was owned by Horn, Kruus and Wrede families. The new manor house building was started in 1685 and completed in 1723.
References:Dryburgh Abbey on the banks of the River Tweed in the Scottish Borders was founded in 1150 in an agreement between Hugh de Morville, Constable of Scotland, and the Premonstratensian canons regular from Alnwick Abbey in Northumberland. The arrival of the canons along with their first abbot, Roger, took place in 1152.
It was burned by English troops in 1322, after which it was restored only to be again burned by Richard II in 1385, but it flourished in the fifteenth century. It was finally destroyed in 1544, briefly surviving until the Scottish Reformation, when it was given to the Earl of Mar by James VI of Scotland. It is now a designated scheduled monument and the surrounding landscape is included in the Inventory of Gardens and Designed Landscapes in Scotland.
David Erskine, 11th Earl of Buchan bought the land in 1786. Sir Walter Scott and Douglas Haig are buried in its grounds.