Kew Gardens, London: A UNESCO Heritage Site, London, England

London has four UNESCO World Heritage Sites, but one - the Royal Botanic Gardens at Kew - is less visited than the others. Each of the others - the Tower of London, Westminster Abbey and the Houses of Parliament, and the Greenwich Museums - attracted more than 2.5m visitors in 2017. Plus countless more who just stood outside to admire the buildings and take selfies. Yet Kew Gardens only had 1.8m visitors last year. It’s still an impressive number, but why so many fewer than London’s other UNESCO sites?

The Royal Botanic Gardens are much more than “just another botanic garden”. There are several strands to the UNESCO listing, starting with the fact that Kew Gardens has been at the forefront of scientific research since it was established in 1759. Its collections of living and conserved plants are still central to international research in botany and ecology. Secondly, several landscape architects, including the great Capability Brown, contributed to the gardens, making it a sort of living museum of garden design through the centuries. In addition, the gardens are home to 44 historic buildings, including the famous Pagoda and the Victorian greenhouses.

Then there are the gardens themselves, which became an inspiration for similar gardens around the world. Set in 326 acres and incorporating a number of former royal estates, they take you on a journey through different parts of the plant kingdom. There are avenues devoted to single trees, like holly or cherry; areas planted with bamboo or rhododendrons; and lilies in the ornamental ponds. The surroundings are important too, with the River Thames on one side and Richmond Park on another. And if you walk along the central Syon Vista you will have an uninterrupted view across the river to Syon House, a grand manor house from the 16th century. ...... (follow the instructions below for accessing the rest of this article).