The National Trust at Petworth House is linking up with the town's Cottage Museum on Saturday (September 13) to provide free access as part of Heritage Open Days.
And at Fernhurst there will be two days of free admission to the site of a former iron works where cannon were made.
Heritage Open Days, which take place every September, offer free access to properties that are usually closed to the public or charge for admission.
For the first time the National Trust, which will be opening ten of its Sussex properties for free, is working with the trustees of Petworth Cottage Museum to enable visitors to appreciate the early 20th century contrast between the lives of the family in the great house and their seamstress, Mary Cummings, who lived in a humble estate cottage in High Street.
Visitors to the house on Saturday, as well as seeing its fascinating 17th-century range of buildings in the woodyard for the first time, can take advantage of a guided walk to the cottage museum.
A unique event planned to capture some of the spirit of the time when the iron industry was alive and thriving in Fernhurst is taking place on both Saturday and Sunday (September 13 and 14)from 10.30am to 5pm.
The iron works at North Park are among the best preserved in the country and Heritage Lottery funding has been given to develop a conservation management plan to achieve even more.
Apart from the interest of the site itself, attractions include the three regiments of The Sealed Knot re-enactment society showing their skills with pike, sword and musket, Gosport Living History Society and medicines of the time, Inside History producing food of the time, flint knapping and plant medicine.
There will be guided tours of the iron works and books available about their history.
Several hundred people lived there with their families to keep the works running 24 hours a day.
The site is a mile west of Fernhurst and will be signed from the crossroads in the centre of the village.
Nationally, more than 3,000 events will be taking place during Heritage Open Days, co-ordinated by the Civic Trust in partnership with English Heritage.
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