A Windmill Tour of South Holland
South of Rotterdam, where the Lek and the Noord rivers meet, nineteen windmills still stand in two long files across a reclaimed marsh called the Alblasserwaard. This is Kinderdijk, the best-known cluster of polder mills in the Netherlands and a UNESCO World Heritage Site since 1997. But Kinderdijk is only the most famous stop on a longer story: the province of South Holland is threaded with drainage canals, low dikes, and the quiet remains of a centuries-old fight to keep farmland dry below sea level. A tour through this landscape says as much about water engineering as it does about windmills themselves.
Land below the sea
Much of South Holland sits at or below sea level, on soil that is a mix of river clay and peat. Peat compresses and oxidizes once it is drained for farming, so reclaimed land keeps sinking even after it has been won from the water. Rainwater and river seepage collect in these low basins, known as polders, and have nowhere to drain naturally. From the Middle Ages onward, Dutch communities organized themselves into water boards, or hoogheemraadschappen, to manage dikes, ditches, and pumping works collectively, because keeping a single polder dry only works if every neighboring polder is managed the same way. Windmills became the practical answer to a problem that boils down to simple hydraulics: how do you lift water out of a basin that sits lower than the rivers and canals around it, using nothing but the wind.
The Alblasserwaard, the polder behind Kinderdijk, is a good example of how this played out over centuries. Farmers and monasteries drained the marshland gradually starting in the medieval period, digging ditches to carry water toward the rivers. As the peat soil settled and shrank, the polder floor dropped further below the surrounding river levels, and gravity alone could no longer carry the water away. By the time windmills were introduced to the area, drainage had become a permanent, mechanical necessity rather than an occasional task, and it has remained one ever since, long after the windmills themselves stopped being the machines doing the lifting.
The windmills of Kinderdijk
At Kinderdijk, two parallel rows of mills known as the Nederwaard and the Overwaard were built in the 1740s to drain the Alblasserwaard polder into the Lek river. The Nederwaard row consists of round, thatched stone tower mills, while the Overwaard row is made up of thatched hollow-post mills of a slightly older design. Together with a scattering of further mills and a historic pumping station nearby, the site preserves the largest concentration of old windmills in the Netherlands. The mills worked in relay: each one lifted water from a lower ditch into a slightly higher storage canal, passing it along the chain until it could be discharged into the river, usually timed to periods when the river level was low enough to receive it. It is an elegant solution built entirely from wood, brick, thatch, and wind.
How a polder mill moves water
Inside a polder mill, the sails turn a horizontal shaft connected through gears to a scoop wheel or, in later designs, an Archimedean screw, both of which lift water a short distance with every rotation. Because a single mill can only raise water a limited height, drainage of a deep polder like the Alblasserwaard required lifting the water in stages, from ditch to intermediate basin to river. Millers lived inside these mills with their families, in cramped quarters built around the machinery, and their work depended entirely on watching the sky. Sails had to be reefed or spread according to wind strength, and the whole cap of the mill, carrying the sails, could be turned to face the wind using a long tail pole from the ground. In an unwatched storm a mill could be damaged or destroyed within minutes, so the miller's vigilance was as important as the machinery itself.
The sails themselves carried a language of their own. Millers set the angle and position of the sails to signal events in the village, a pattern of rest for a birth, another for mourning, another for a wedding, so that a mill standing still or turning at a particular angle could tell neighbors what had happened before any word passed between houses. That tradition, born from necessity in an era before quick communication, survives today mostly as a ceremonial gesture on special occasions, but it is a reminder that these machines were never purely functional. They were also the most visible object in a flat landscape, and they carried meaning well beyond drainage.
The legend of the cradle
The name Kinderdijk, meaning children's dike, is often explained by a folk legend tied to the St. Elizabeth's flood of 1421, one of the worst floods in Dutch history, which breached dikes and drowned large stretches of the region. According to the story, after the floodwaters receded, villagers found a cradle floating against the dike with a cat inside, balancing itself to keep the cradle from tipping, and a baby asleep inside, unharmed. Whether or not the tale is literally true, it captures something real about the region's relationship with water: a landscape shaped by catastrophic floods, rebuilt through patient engineering, and remembered through stories passed down alongside the dikes themselves.
From wind to steam and diesel
Wind was a reliable but limited source of power, dependent on weather and unable to work at all during calm spells or when sails needed repair. Starting in the nineteenth century, steam-powered pumping stations began to take over drainage duties across the Dutch polders, offering constant power regardless of wind. Diesel and later electric pumps followed in the twentieth century, and one by one the windmills of South Holland were retired from daily service. Rather than being demolished, many were preserved, both for their historic value and because local communities recognized what they represented. At Kinderdijk today, the mills are maintained as a working heritage site: several are still fully operational and are set turning on open days, a handful are inhabited, either by resident millers or as private homes, and the surrounding pumping infrastructure, old and new, still keeps the Alblasserwaard dry.
Beyond Kinderdijk
South Holland's mill heritage is not limited to Kinderdijk. Around Gouda, Leiden, and Delft, individual polder mills survive along canals and drainage ditches, some restored as private residences, others opened seasonally by local heritage foundations, and clusters known as molenviergangen still stand in a few villages where four mills once worked a shared stretch of polder. Schiedam, on the outskirts of Rotterdam, offers a different kind of contrast: its mills are not polder drainage mills but tall industrial grain mills, built high enough to catch wind over the surrounding rooftops and warehouses, among the tallest traditional windmills in the world. Seeing both traditions within the same province, drainage mills built low and close to water, and grain mills built tall and close to the harbor, gives a fuller picture of how central windmills once were to Dutch daily life, in ways that had nothing to do with tourism and everything to do with survival and trade.
A visitor with time to spare can trace a rough line from one tradition to the other in a single day, starting among the low, thatched drainage mills of Kinderdijk in the morning, moving inland past the quieter, single mills that still dot the polders around Gouda, and finishing the afternoon under the towering grain mills of Schiedam as the light turns golden over the harbor. Few provinces anywhere pack this much windmill variety into so small an area, and fewer still let a visitor see, in one trip, both why the mills were built and what happened once wind was no longer the only option.
Explore on the map
Kinderdijk, Schiedam, and the scattered polder mills between Gouda and Delft can all be located on our interactive map, along with notes on which mills are open to visitors and which operate only on demonstration days. Use it to plan a route through South Holland that follows the water rather than a checklist, starting at the rivers where the land was first won and ending among the mills still standing guard over it.