This medieval plan, spanning four large sheets of vellum stitched together, charts the water system installed in the 1430s that served the Carthusian monks of the Charterhouse. It was a working document that has been annotated by different hands over many decades, and was eventually replaced three times by later documents recording repairs and extensions.

The plan records water pipes, gutters and cisterns running from Islington on the left of document to the Great Cloister of the Charterhouse on the right. On its way, the water system follows the highway, passing landmarks such as St John’s Priory, the Mill Hill, the nun’s field of Clerkenwell, and the Pardon Chapel.
As well as being an incredible record of fifteenth-century infrastructure, the plan of the water system gives us a unique insight into the Charterhouse itself in its medieval heyday. It shows that, in addition to the monastic church, the site comprised facilities including kitchens, a laundry, and a brew house. The 24 cells of the Great Cloister, each labelled with a letter of the alphabet, can be seen surrounding the cistern of the water system.

There are still some tantalising glimpses of the medieval Charterhouse today. Just half of one side of the Great Cloister still exists, including the doorway of cell ‘B’ from the diagram. This part of the cloister was developed into a covered garden gallery in the sixteenth century, and is now known as the Norfolk Cloister, named after a later owner of the house, Thomas Howard, the fourth Duke of Norfolk. A piece of the monks’ Chapter House – seen in the south-east corner of the plan – exists today as part of the current chapel tower, and features a squint – an opening in the wall looking down from the Chapter House to the high altar of the monastic church and the tomb of its founder, Sir Walter Manny.

Visitors to the Charterhouse today can discover more of the medieval monastery and the lives of its monks by booking a guided tour.

The 1431 plan of the water system is on display in our museum, along with many other artefacts illustrating the fascinating medieval history of the Charterhouse.