Sunken Gardens: The 4-acre tropical garden, which opened in 1935 and was refurbished by city parks crews a couple of years ago, features a butterfly garden and aviary, water ponds and flower displays. 1825 Fourth St. N, St. Petersburg. 10 a.m.-4 p.m. Wed.-Sun. $5 adults, $3 ages 55 and older, $2 ages 3-11. (727) 551-3100.