TO MARK its 10th anniversary on Easter Sunday, 2 April, English Heritage (071-973 3396) is offering free entry to its more than 400 historic sites, which include Stonehenge, Hadrian's Wall, Rievaulx Abbey, Dover Castle and Thetford Priory.

Its programme of open-air concerts this summer includes Tosca by the Welsh National Opera at Kenwood, Hampstead, on 19 June, a Glenn Miller Anniversary Concert on 24 July, and English National Opera's The Barber of Seville, on 21 August, both at Marble Hill, Twickenham.