Den Aalshorst, also De Aalshorst, is a country house in the hamlet Millingen in Overijssel (Dalfsen municipality).
Until the seventeenth century the Aalshorst was an ordinary farm. In the feudal registers of the bishop of Utrecht, both the yard itself as the tenth over from the end of the fourteenth century. In 1394 it was pawned by Hadewych, wife of Johan ies Schule der Borch, whereupon it in 1412 was inherited by her son Symon
In 1644 the couple Zwolle Mr. James Vriesen and Helena van der Beke built here a 'spieker' later known as Freeze Nail. It had two fire places in 1675 and in 1682, three fire places and an oven.
James and Helen were married in 1640 at Windesheim. James was a son of the Zwolle city secretary Helen and Timing Vriese a daughter of the Zwolle Treasurer Robert van der Beke.
In 1720 James' grandson, Jacob Vriesen, son of Diederik Vriesen, replaced the 'spieker' by the present house and then were also built the two building houses on either side of the square.
In 1752 Jacob married daughter Machteld Johanna Geertruid with the Amsterdam based military Jan Willem de Famars. After his death she lived Aalshorst in 1795. In 1807, she was buried in the church in Zwolle.
In 1807, the Aalshorst was sold to Zwolle merchant Henry Ignatius Christianus Kempen who died in 1819. In 1832 it was the property of Louis Aalshorst Rhijnvis Feith (1783-1845), son of Rhijnvis Feith. Feith was married to Johanna Theodora baroness of Dedem (1790-1873), from the nearby manor Den Berg. After her death it came into the possession of William Baron of Godert Dedem.
In 1908 the estate was placed in an operating company.
Around the house there are several elements of the eighteenth-century park construction preserved, such as the canals, and two grand canals: both lie in the axis of the house, one in front the other behind the house. The main landscaping lies next to the house, on the south side.