during the early independence years. 1986–present The Singapore Botanic Gardens was put under the charge of the National Parks Board. The Gardens was revitalised with new and improved public amenities, research facilities and training facilities (1990–2005). Here, the focus is on Garden City Vision, Horticulture, Taxonomic + Biodiversity Research, Recreation and Education. A "Tyersall extension" to the Gardens was announced in 2009. A total of 18 hectares of land was added in expanding the Gardens by almost four times its original size in 1859. Known as the Gardens' Learning Forest when it was fully completed in 2018, the extensions included a Forest Conservation Interpretive Centre and a Natural History Art Gallery, housed in colonial buildings more than a century old. The Learning Forest showcases the best of tropical trees that grow under local conditions and strengthen the Botanic Gardens' position as a premier institute for research, conservation and education. Visitors are able to appreciate this unique collection of trees and plants through various thematic walks within the Learning Forest featuring giant trees, trees with interesting forms and barks of various textures, a conservation collection of rare fruit and nut species and a bamboo garden. Also included is a flood protection scheme for the main shopping district of Orchard Road and its surroundings and a water detention pond with capacity to hold excess storm-water of about 15 Olympic-size pools. Attractions The garden is bordered by Holland Road and Napier Road to the south, Cluny Road to the east, Tyersall Avenue and Cluny Park Road to the west and Bukit Timah Road to the north. The linear distance between the northern and southern ends is around . There are a number of entrances at different zones of the gardens, though the Tanglin Gate facing Holland Road in the south is the grand entrance. National Orchid Garden The National Orchid Garden is the main attraction within the Botanic Gardens. Located on the mid-western side of the Garden, the hilly three-hectare site has a collection of more than 1,000 species and 2,000 hybrids of orchids. There are a number of attractions within the Orchid Garden, including the following - Burkill Hall: Burkill Hall is a colonial plantation bungalow built in 1886. It used to be the director's house and was named in honour of the only father and son pair to hold the post of Director of Singapore Botanic Gardens, Isaac and Humphrey Burkill.