Enter the Royal Botanic Gardens, as Kew Gardens are officially known, and you are enveloped by blazes of color, extraordinary blooms, hidden trails, and lovely old follies. Beautiful though it all is, Kew's charms are secondary to its true purpose as a major center for serious research. Academics are hard at work on more than 300 scientific projects across as many acres, analyzing everything from the cacti of eastern Brazil to the yams of Madagascar. First opened to the public in 1840, Kew has been supported by royalty and nurtured by landscapers, botanists, and architects since the 1720s. Today the gardens, now a UNESCO World Heritage Site, hold more than 30,000 species of plants, from every corner of the globe.
Architect Sir William Chambers built a series of temples and follies, of which the crazy 10-story Pagoda, visible for miles around, is the star. The Princess of Wales conservatory houses 10 climate zones, and the Rhizotron and Xstrata Treetop Walkway takes you 59 feet
up into the air. Two great 19th-century greenhouses—the Palm House and the Temperate House—are filled with exotic blooms, and many of the plants have been there since the final glass panel was fixed into place. Unfortunately the enormous Temperate House is closed for maintenance until 2018, so until then you won't be able to gawk at the largest greenhouse plant in the world, a Chilean wine palm planted in 1846 (and so big that you have to climb the spiral staircase to the roof to get a proper view of it).
To get around the gardens, the Kew Explorer bus (£4.50) runs on a 40-minute, hop-on, hop-off route, starting at the Victoria Gate, every hour 11–3. Free guided tours, run by volunteers, are given daily at 11 and 1:30, plus special seasonally themed tours at noon. Discovery Tours (£5), fully accessible for visitors in wheelchairs, are also available with advance booking, as are bus tours specifically for groups of visitors with limited mobility; usually run Tuesday, Wednesday, and Thursday, they are priced at £30 per bus.