Events & Activities What's On/Events Bourn Windmill Open Day Sunday 15 September, 2pm-4pm Bourn Mill is one of the oldest in the country, set in beautiful scenery. On five Sundays during the summer the mill is opened and guides will show you how the mill works and tell you the history of this incredible building. Not only can you see inside, you can also have a go at the incredible task of turning the whole mill on its post - an amazing sight. The mill is owned by local charity CambridgePPF and run by dedicated volunteers. Tea and cakes available to purchase. Members free, non-members £3 adult, £1 per child. No need to book.