Nonguests are welcome to visit Hotel New Ōtani's beautiful 400-year-old Japanese garden, which once belonged to a Tokugawa regent. Including vermilion arched bridges, koi (carp) ponds and a waterfall, it is one of Tokyo's most enchanting outdoor spaces. Return in the evening to see the garden illuminated with LED lights.
Ask at reception whether it's also possible to access the rooftop Rose Garden, which is planted with tens of thousands of the flowers.