These Sphenodon are living free in a sanctuary established within a predator-free fenced area within the bounds of the city of Wellington. They were introduced there in 2005 and are living free within the sanctuary.
There are no accessible areas where non-introduced populations of Tuatara can be seen in New Zealand. This population is the only mainland population of Tuatara in New Zealand.
You can read about the re-introductions here - http://www.massey.ac.nz/~darmstro/nz_projects.htm#tuatara
The goal of these reintroductions is recreate breeding populations on predator free areas.
Although some might look at these animals as "captive" because the area they inhabit is fenced, it is akin to a mammal being reintroduced to the fenced boundaries of a national park. They are heavily monitored but are living a wild life within their 225 hectare habitat.