Ethnikos Kipos (National Gardens), Athens
Southeast of Syntagma Square
Concierge.com's insider take:
When your lungs are dusty and you need to see green, slip inside the verdant, semi-tropical National Gardens, established in 1840. Also useful for kidsthere's a playground, a children's library with toys (and blessed AC), and a lot of ducks.
Open daily 7 am to sunset.