Flanked by the castle and the River Taff, Bute Park was donated to the city along with the castle in 1947. With Sophia Gardens, Pontcanna Fields and Llandaff Fields, it forms a green corridor that stretches northwest for 1.5 miles to Llandaff. All were once part of the Butes' vast holdings.

　　In Cooper's Field, the part of the park just west of the castle, is a stone circle, erected in 1978 when Cardiff hosted the National Eisteddfod. Such so-called gorsedd stones are found all over Wales where eisteddfodau have been held.

　　Marked out in brick on the lawn nearby are the dimensions of the 13th-century Blackfriars Priory, which was destroyed in 1404 when Owain Glyndŵr attacked Cardiff and later rebuilt, only to be finally vacated in 1538 when Henry VIII dissolved Britain's monasteries.