Blickling Hall opens its doors to allow visitors behind the scenes this weekend. SIMON PARKIN discovers what's behind the historic doors at other great National Trust properties.

BLICKLING HALL

Blickling Estate and Gardens, on B1354, signposted off A140 Norwich/Cromer, Wed-Sun 11am-5pm, �10.75, �5.35 children, �20.70 family, 01263 738030, www.nationaltrust.org.uk

Just what is behind those closed doors? This weekend offers a chance to visit parts of Blickling Hall not on the usual visitor route, including a climb to the attics or a visit to the basement. A must for the curious, the Back Stage Pass tour on March 31 (�5 additional charge). Built in the early 17th century, Blickling is one of England's great Jacobean houses. The spectacular Long Gallery houses one of the finest private collections of rare books in England, and you can view fine Mortlake tapestries, intricate plasterwork ceilings, an excellent collection of furniture and paintings, as well as the newly re-stored 19th century Hungerford Pollen painted ceiling. Outside the glorious gardens are beautiful all year round — and currently have thousands of spring bulbs.

OXBURGH HALL

Oxburgh Hall and Gardens, off the A134 at Stoke Ferry, Mon-Wed/Sat 11am-4pm, Sun 11am-5pm; daily 11am-5pm from April 2, �7.80, �3.9 children, �19.50 family, 01366 328258, www.nationaltrust.org.uk

Oxburgh's secret doors and priest's hole make this a house of mystery and history. Step back in time through the magnificent Tudor gatehouse into the dangerous world of Tudor politics when the doors open this weekend.

Home to the Bedingfeld family since 1482, this stunning red-brick house charts their history from medieval austerity to neo-Gothic Victorian comfort. As well as early Mortlake tapestries, Oxburgh houses beautiful embroidered hangings by Mary, Queen of Scots, and Bess of Hardwick. Panoramic views from the roof look out over the Victorian French parterre, walled orchard, kitchen garden and a Catholic chapel.

HORSEY WINDPUMP

Horsey Mere, B1159, Horsey, Sat-Sun 10am-4.30pm; daily 10am-4.30pm from April 2, �2.50, �1 children, 01263 740241, www.nationaltrust.org.uk

Standing at the closest point the Broads come to the sea, Horsey Windpump is surrounded by internationally important wildlife habitats. From the top you get stunning views of Horsey Mere and across the broadland landscape to the coast. The Horsey Estate is of exceptional nature conservation interest, notably for breeding birds and wintering wild-fowl. It was acquired by the National Trust in 1948 from the Buxton family, who continue to manage the Horsey Estate with nature conservation as a priority. The reserve has a new nature garden.

SHERINGHAM PARK

Sheringham Park, main entrance at junction A148/B1157, park open dawn to dusk; visitors centre 10am-5pm daily, free admission with a charge for car parking for non-members, 01263 820550, www.nationaltrust.org.uk

With fabulous displays of rhododendrons and azaleas and viewing towers providing amazing coastal views, Sheringham Park is one of the finest examples of the work of renowned author and landscape designer Humphry Repton. Repton was a minor squire who in 1788, aged 36, decided to take up the profession of landscape gardener. He worked at many major houses and estates, including Tatton Park, Woburn Abbey and Harewood House, but mixing architecture as well as garden design, Sheringham Park is regarded as the most successful of his projects.

ICKWORTH HOUSE

Ickworth House and Park, A143, three miles from Bury St Edmunds, Mon-Tues/Fri-Sun 11am-5pm; park open daily 8am-8pm, �10.40, �5 children, �25.80 family, 01284 735270, www.nationaltrust.org.uk

Ickworth's huge central Rotunda, flanked by two massive wings, dominates this eccentric house built by the equally eccentric 4th Earl of Bristol, who dreamed of creating an Italianate palace within an English landscape.

This impressive building houses important collections of paintings (including work by Vel�zquez and Titian) and fine family portraits (several by Gainsborough). The idyllic parkland includes a vineyard and dense woodland offering miles of walks and cycle rides.