The event runs from Friday to Sunday (May 3-5) and aims to celebrate architectural excellence. More than 50 buildings will be opened up to the public.
Festival organiser Jessica Halliday said Christchurch is a great place to stage the event.
"There's both a rich history of architecture, plus many of the new buildings that have been built since the earthquakes.
"So there's an amazing range of buildings to explore."
"People love having a nose (around).
"There's nothing like an invitation to come into a place that you're not sure if you're allowed to go into.
"And people love being nosey.
"So we give people an excuse to go and have a nose in buildings they wouldn't otherwise get to go inside."
The organisers are delighted to be celebrating the festival's fourth year.
"There are two main reasons why we created the festival," Halliday said.
"And the second reason we do it is to foster a greater sense of belonging and connection in the city."
The unique experiences this weekend will include a roof-top tour of the former High Street Post Office building and three different construction sites.
But bookings are already full for the behind-the-fence tours of Christ Church Cathedral, the Court Theatre and the Youth Hub building.
However, Halliday said 34 tours don't require any bookings. People can just turn up on the day to enjoy a special architectural experience.
Visit openchch.nz for bookings, building-specific accessibility or more information.
- By Geoff Sloan, made with the support of NZ On Air
