The garden at Buckingham Palace has 45 different types of mulberry trees, a trend started in 1608, when James I tried to rear silkworms there. The garden also contains 325 wild-plant species, 85 species of oak (the tree of England), and 30 species of breeding birds. This summer, from July to September, unique access to the Queen’s private garden is on offer. Prepare to wander and picnic, but be sure to book tickets in advance. —L.J.