Aberdeen's success in the Britain in Bloom competitions is often attributed to Johnston Gardens, a small park of one hectare in the west end of the city containing many different flowers and plants which have been renowned for their beauty. In 2002, the garden was named the best garden in the British Islands. Seaton Park, formerly the grounds of a private house, is on the edge of the grounds of St Machar's Cathedral. The Cathedral Walk is maintained in a formal style with a great variety of plants providing a popular display. The park includes several other areas with contrasting styles to this. Union Terrace Gardens opened in 1879 and is situated in the centre of the city. It covers in the centre of Aberdeen bordered on three sides by Union Street, Union Terrace and Rosemount Viaduct. The park forms a natural amphitheatre located in the Denburn Valley and is an oasis of peace and calm in the city centre. A recent proposal to build a three-storey concrete and steel superstructure in place of the gardens, part of which will provide a commercial concourse, has proved highly controversial.