You can wander round the 34km of tracks and admire the wildlife any day between 10am and 5pm, but we were here on one of their guided Nocturnal Tours which start just as the sun goes down.
As we walked from the visitor centre, through the protective gate to the bush the evening chorus from the birds was deafening, with tui, bellbirds, North Island saddlebacks and stitchbirds combining to produce an extraordinary melody.
On the lake, which was once the city's water reservoir, a few scaup and pateke swam amid a collection of intruding ducks, flocks of pied and little black shags rested on branches at the waters edge while a kingfisher skimmed the surface looking for insects.
Along the edges of the bush fantails, North Island robins and tomtits, silvereyes and whiteheads flittered about grabbing a last snack before bed.
A chattering kaka flew nosily just above the treetops and high above a kahu floated silently and sinisterly. Finally, as darkness fell, the call of a morepork echoed across the sanctuary valley. We were in a New Zealand not seen, or rather heard, for maybe 200 years.
As we made our way quietly into the trees Katie whispered the remarkable story of how over the past 12 years a group of enthusiastic volunteers sealed the valley off behind a predator proof fence, eradicated 14 different predators ranging from cats and stoats to rats and possums, and progressively re-introduced 14 indigenous species that had been lost from the area.
From somewhere inside the bushes came the distinctive scratching sound of a weta, though which of the three varieties found here wasn't clear. I've always been fascinated by the giant wetas - among the largest insects in the world, older than the tuatara and basically unchanged over the past 150 million years - so I hoped it was one of them.
When I mentioned this, Katie told the story of how when the giant weta were first released they were fitted with very expensive tiny transmitters, to track their movements. "The scientists were very puzzled as to why one of the wetas seemed to be down on the edge of the lake. Eventually they realised that one of our rare giant wetas had been swallowed by an eel, transmitter and all, so it was the eel they were tracking."
Suddenly the silence was broken by the harsh call of a kaka. "They're very bad at going to bed," said our guide. "They're like teenagers. They often keep playing when they should be resting."
Soon we arrived at a second fence and Katie began to search on the other side with the red beam of her torch. "Ah," she said, "there she is." And there in the beam was a female tuatara, a survivor from the age of the dinosaurs, sitting in the mouth of her burrow.
I have seen tuatara before, I've even held one at the marvellous Southland Museum, but this female was bigger than I'd expected. We walked around to view the female from a different angle and found she had moved to face us again. "They're much more active at night," Katie said with a grin. "They come out of their burrows and run around and eat other endangered species."
Leaving the tuatara behind we made our way up into the hills above the lake hoping to see a little spotted kiwi. Those hopes were raised when from very close by came the distinctive cry. "That's a male," said our guide. "It's more high-pitched than the female."
The only question was whether it was a real kiwi or a recording being played by a group of kiwi researchers we had met shortly before. Fortunately, just round the corner we met the researchers again and, no, it was a real kiwi we had heard.
The tracks here should have been dark, because of the heavy leaf cover, but in many places the banks alongside were lit up by clusters of glow worms. We stopped to check them out and inspect the sticky threads they hang down to trap any unwary insects attracted by the light.
Then there was another call. "Another male. I don't think it's the same one." There were obviously plenty of kiwi here - it's estimated that the 40 originally released in the sanctuary have increased to over 100 - but would we see one?
The answer came soon afterwards in the form of a snuffling, rustling noise in the bushes, and there she was. "I think it's a female," whispered Katie, as we watched, entranced, while the kiwi spent several minutes poking her bill into the debris on the forest floor in search of food, so close we could have touched her. It was a magical experience.
As we left the sanctuary I couldn't help reflecting that they do things well in Wellington. Auckland has Tiritiri Matangi, which is an equally magical place, but it's not in the middle of the city.
Earlier in the day we had gone on a guided walk through the city centre which confirmed, yet again, that while Auckland is still squabbling about what to do with its waterfront, Wellington has created a fantastic place, full of works of art and places for children to play, museums and art galleries, open spaces in which to kick a ball or read a book, cafes in which to enjoy a coffee or a meal.
The capital has also been vastly better at preserving its old buildings and making effective use of them. The old city library is now the art gallery and, when we were there, it was resplendent in coloured dots as a tribute to an exhibition by the dotty Japanese artist Yayoi Kusama.
The Stock Exchange now lives on the waterfront in an old timber company building having, as our guide told us with relish, "been bribed by the Wellington City Council not to move to Auckland."
The former Wellington Harbour Board building now houses the Academy of Fine Arts, with several excellent exhibitions, while still retaining outside the charming memorial to Paddy the Wanderer, a dog who once captured the hearts of the city's watersiders and taxi drivers.
The old BNZ building is now an excellent shopping centre but, in the basement, you can see the remains of the sailing ship Inconstant, which in 1849 ran aground and was bought by local businessman John Plimmer and used as a sort of shopping arcade.
And the old National Bank Building now houses Logan Brown, Cuisine magazine's supreme restaurant of the year, where we had a superb meal off their bistro menu before heading out to see the little spotted kiwi.
CHECKLIST
Getting there: You can find out about the Scenic Rail Pass, the cheapest way to see the country by rail, at tranzscenic.co.nz.
What to do: Visit the Karori Sanctuary Trust website and find out more about the nocturnal encounter at visitzealandia.com.
Further information: See wellingtonnz.com.
Jim Eagles travelled New Zealand by rail with help from KiwiRail, Air New Zealand and the regional tourism organisations along the way.
