Baldwin Street

Baldwin Street, at Dunedin's Northern end is reputed by the Guinness Book of Records  as being the steepest street in the world.   35% gradient = 1:2.86  You are advised against taking a car up the street so no cheating please. It is a very invigorating walk to the top on a cold day. Only about a ten minute walk but you can sure feel it.
At its maximum, the slope of Baldwin Street is approximately  (19° or 35%) - that is, for every 2.86 metres travelled horizontally, the altitude rises by 1 metre.

Once at the top, just get your breath back and enjoy the view. There is a drinking fountain up here too.
After this walk, lunch in the Botanical gardens would be the perfect compliment, followed by a stroll. Then let the kids feed the ducks or just play around the park.

Looking down
35 degree gradient =1:2.86

The street's steepness was unintentional. As with many other parts of Dunedin, and indeed New Zealand, streets were laid out in a grid pattern with no consideration for the terrain, usually by planners in London.

The street is the venue for an annual event in Dunedin, the "Baldwin Street Gutbuster". Every summer since the mid-1990s (usually in February), this exercise in fitness and balance involves athletes running from the base of the street to the top and back down again. The event attracts up to 1000 competitors annually.