It was built on the site of what was known as the Child Estate. (en.wikipedia.org)
One of the bridge rules is that the bridge has to be built on site in only a handful of minutes using only hand tools and a limited number of students. (cooperalumni.org)
More advanced ones, with sliding glass doors or a deck, for example, will need to be built on site by a specialist. (idealhome.co.uk)