Members of the public will be invited to walk through one of the nearly-completed City Rail Link (CRL) tunnels underneath Auckland in November.
CRL posted on its Facebook page that a one-off, one-day public walk is being planned in a section of the 3.45km tunnels.
Tickets will be limited, with only 10,000 people allowed to come through during the event, which will take place on November 17.
Ticket holders will be arranged into groups which will set off hourly between 8am and 5pm.
Tickets will be free with a limit of six per person, and will be available from November 6.
CRL said the finer points of the event are still being planned, and anyone who is interested should follow them on Facebook for more details in the near future.
A similar event in 2017 saw members of the public walk through the new Waterview Tunnel before it opened, and thousands of people attended.