The thirty-acre Castle Park sweeps north from the castle down to the River Colne, taking in formal gardens, the boating lake, a play park, and a bandstand. The combination of Norman keep, medieval ruins of St Botolph's grange, and the lower riverside grounds gives a wide range of paths in a small space — easy to spend a couple of hours on a sunny afternoon.
In summer the park hosts open-air concerts and the Colchester Free Festival; out of season the riverside walk down to the Hythe is one of the prettiest in town. Free entry, open daily.