It was identified as a stair tower with privy due to it being open on the water front at floor level.

[3] What sets Polanen Castle apart from other solitary tower houses is that it was built on a large site.

[10] On 6 November 1295 Floris V, Count of Holland granted the fief Polanen 'with the house' to Philips van Duvenvoorde.

[11] He was a junior member of the Van Duvenvoorde family, which was seated at Duivenvoorde Castle.

John was helped by his uncle Diederik van der Wale, who e.g. gifted the very profitable wind mill at Voswijk near Monster.

(The house at Polanen, upper and lower, and the terrain on which it stands, including the old court inside the outer moat.).

The war erupted in earnest after William of Holland entered his county in February 1351.

[14] On 1 June 1351 the battering ram which had served at Rosenburg Castle, and a new one, were ordered to Polanen.

These were called mol or mole, and would provide cover for its crew while they filled the moat, and then broke down the wall by battering.

Shortly before 1 June the construction of a siege tower for Polanen had started in The Hague.

On 8 June Lord Willem van der Wateringe arrived with 24 English.

A quick destruction to render it permanently unusable would have entailed pushing most of it into the moat, but no signs of that were found.

The Cod faction and the city of Delft opposed his regency, and so the Hooks were on the side of regent Albert.

[18] In the night of 22–23 September 1392 the count's mistress Aleid van Poelgeest was murdered.

[17] In the 1394 accounts of the county, money was paid to a mason for 10 weeks of breaking bricks from the castle.

[10] Another contractor was paid for the 28 days that he spent to fill the moats, and to transport the brick to The Hague.

[19] Their fourth child, Catharina (1371-1421) married Hendrik III van Naaldwijk (1367-1419).

In 1550 her daughter Margaretha, who was married to Jan de Ligne, inherited Polanen.

[9] During the Eighty Years' War Charles of Arenberg remained loyal to the King of Spain, leading to the sequester of his possessions in Holland.

Frederick Henry, Prince of Orange bought part of the rights and land for 360,000 guilders.

[23] In late March 1940 Archeologist Jaap Renaud succeeded in borrowing some mobilized soldiers from Captain Roorda van Eysinga, so he could do a preliminary investigation.

This would entail reshuffling the ground till 5 meters below the surface, and so a new thorough excavation was planned.

[2] This new excavation completed the picture about the tower house, its bailey, and the location of the succeeding manor and farm.

Above that was a normal sediment layer with almost no artefacts, leading to doubts about whether the castle was inhabited after 1351.

It confirmed the 1394 demolishing by a mason, which led to moving the bricks to The Hague for reuse.

The medieval bricks, so called kloostermoppen, were stored in order to use them in renovations, but were later judged unsuitable for that purpose.

The then owner of villa Nieuw Polanen used these kloostermoppen to build a folly (pseudo-ruins) in his garden.