Kennington Park has got a pretty fascinating history. Before it was reopened in its current incarnation in 1854, the site held public executions until 1800, was South London's speakers' corner, and one of London's earliest known cricket venues, hosting matches as far back as 1724. It's also where the Chartists gathered for their biggest 'monster rally' in 1848.
The park today is well covered with trees and flowers and all that, so it's ideal for walking and lounging alike. It's also got pretty great facilities, with a paddling pool, free cricket nets, football pitches, astroturf, hockey court, tennis courts and skateboarding facilities.
Some of these facilities are chargeable and some are free: check out the
website for more info.
Please note: the park closes approximately 15 minutes before sunset every day.