Overseas visitors to the UK's heritage attractions such as theatres, museums and national parks spend more than double per trip compared with domestic tourists , according to a new report.
Foreign travellers spend an average of £560 on such visits, while the figure for UK-based overnight visitors is £210.
A total of £7.4 billion was spent on heritage trips by o verseas visitors last year, the study published by the Heritage Lottery Fund (HLF) found.
Ros Kerslake, chief executive of HLF, said: "T hese new figures reveal just how significant international tourists are to the UK's economy - spending twice as much as their domestic counterparts.
"It is therefore essential that the UK continues to champion our unique heritage in order to attract more visitors, both in the UK and further afield."
The largest economic contribution is made in London, where heritage tourism is estimated to have supported a £5.7 billion boost to the UK economy last year.
But r esearchers found that the sector's relative importance is highest in the North East, Wales and Scotland.
Heritage tourism provides nearly 2% of these regions' total economic output, compared with a UK average of 1.1%.
Bernard Donoghue, of the Association of Leading Visitor Attractions, said: "The economic contribution which heritage makes to local, regional and national economies is, as these figures reveal, hugely significant.
"Our living heritage is rightly valued for its cultural, educational, aesthetic and historical importance but we can now also clearly see that it is an economic driver for inbound tourism to the UK, as well as sustaining domestic tourism too."