Cathays Park is Cardiff's civic quarter — a formal Edwardian park surrounded by grand white Portland stone buildings that make up the city's administrative heart. The City Hall, the National Museum, the Crown Court, the University of Wales registry, the Welsh Office and several other institutions form a coherent ensemble around the lawns, giving Cardiff a proper civic centre that most British cities of similar size lack.
The park itself is well maintained and popular with office workers at lunch. On summer evenings it fills with students from the nearby university. The combination of the buildings and the greenery makes it one of the most pleasant parts of the city to walk through, particularly in spring when the flower beds around the City Hall are at their best.
The ensemble is worth about 20 minutes on foot even if you don't go inside anything — the scale of the Edwardian ambition is still legible and gives a sense of how seriously Cardiff took its new capital status at the start of the 20th century.