St Peter's Church: The Beacon on the Hill has "overseen" much of Whanganui's history.
Local author and historian Murray Crawford, who is a member of Friends of St Peter's, hosted an information session at the Koromiko Rd church on Saturday as part of Whanganui Heritage Month.
St Peter's, which celebrated its 150th anniversary in 2016, has a Category 2 listing with Heritage New Zealand in recognition of its historical significance.
"The church was consecrated in 1866," Crawford said.
"It was originally on the Victoria Ave site now occupied by the Cotton On clothing store and was surrounded by a churchyard with the graves of our early settlers."
St Peter's, an Anglican church, was a replacement for the previous Christ Church which only lasted 20 years.
The new church was built after a big fundraising effort and expected to last only about 50 years.
While it is not the oldest building in Whanganui, St Peter's is the oldest still in public use and still being used for its original purpose, Crawford said.
Saturday's information session drew a good crowd who wanted to know more about the historic church.
"St Peter's has always been there for as long as people can remember," Crawford said.
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"They're quite surprised that it has such an important historical background. It's overseen most of the history of the town and the city of Whanganui.
"I was pleasantly surprised - we had nearly 30 people and the small church lounge was overflowing. There was quite a lot of positive comments afterwards.
"The church has quite a lot of items that have been accumulated over the years - there are various plaques, there are stained glass windows that commemorate various people who have been associated with the church.
"There's also a plaque dedicated to some of the military who served here and relates back to the Battle of St John's Wood in 1847."
A Battle of Britain service has been held at St Peter's every year for "many, many years", Crawford said.
After the session, several people expressed interest in becoming members of Friends of St Peter's.
"We're always open to new members," Crawford said.
Crawford will host another session at St Peter's at 11am on Saturday, August 24, as part of Whanganui Heritage Month.