Parnitha National Park is punctuated by well-marked paths, gorges, springs, torrents and caves dotting the protected area. Hiking and mountain-biking in all four mountains are popular outdoor activities for residents of the city. The National Garden of Athens was completed in 1840 and is a green refuge of 15.5 hectares in the centre of the Greek capital. It is to be found between the Parliament and Zappeion buildings, the latter of which maintains its own garden of seven hectares.