Aldendriel was never meant to repel an army. The brickwork dates back to 1477, but there is no evidence it ever carried siege-worthy walls. What it has is water. A wide double moat wraps the keep and the outer bailey, deep enough to slow a brawl on horseback but not a trained engineer with cannon. This was a defendable house, not a fortress. By the seventeenth century, when the castle was reshaped into the squarish footprint it carries today, even the pretense of defense had been abandoned. The outer bailey grew five gates with brick pilasters and stone capitals, all built for a manor, not a siege. The highest portions of the keep, on the northern and western sides, still hide sixteenth-century timber framing inside their walls.

Willem Liedel was the son of a minor Prussian official. He went to sea as a ship's doctor, sailed for the Dutch East India Company starting in 1735, and a decade later became a free citizen of Batavia in the Indies. Trade made him spectacularly rich. He returned to Rotterdam, settled at the Leuvehaven, and in 1750 made an extraordinary discovery: his grandniece Odilia had married the debt-ridden Comte de Pas, lord of Well Castle and, soon, Aldendriel. In 1754 the Comte bought Aldendriel from the Baron of Dongelberghe for 11,000 guilders. The cash, almost certainly, came from Liedel. In 1763 the renovation that gave the castle its new inner courtyard facade was completed, and an anchor plate marked the date in the wall. The following year, Liedel bought a knight title in Frankfurt. By 1772 he was installed as Lord of Well and Aldendriel, having changed his name to De Liedel de Well.

Liedel's grandson Pierre Guillaume de Liedel became baron of the French Empire under Louis Bonaparte, and was elevated again to the Dutch nobility in 1822. He married Baronin Anna von Schlossnigg, and his two legitimate children both died before he did. In old genealogies a third name sometimes appears without explanation: Marianne von Evers van Aldendriel. The explanation, when it surfaced, was that Pierre Guillaume had carried on an affair with his wife's younger sister Eleonore Philippine. Marianne was their daughter. She could not inherit the lordship of Well, so her father did what he could. He gave her the usufruct of the Aldendriel estate for her lifetime, a workaround for a daughter the family could not legitimize but would not abandon. After her death, the castle changed hands several times. By 1906 a Catholic boys' boarding school occupied some of its rooms.

In 1962 a man named Jacob Adriaan Oudenaarde bought the main building and spent four years restoring it. His daughter Marijke married the dentist Jochem Oerlemans, and the couple raised three sons in the castle's residential rooms. One of them, Reinout, grew up to play Arnie Alberts on a Dutch soap that ran for decades. The 2018 plaque is for him. The pop musician Thijs van Leer, the flute-and-keyboard founder of the prog-rock band Focus, lived in another part of the castle for about a decade starting in 1993. Manto Ledeboer bought the place in 2001 and still lives there. The outer bailey runs as a private event venue, hosting weddings and corporate parties for crowds of 50 to 350. There is no public access to the main house. The moat keeps the curious at arm's length, just as it always has.