Merces Tower, better known locally as Curitiba's Panoramic Tower, gives one of the clearest high views over the city. From above, Curitiba's avenues, parks, and denser central blocks make more sense than they do at street level.
The visit is short, but useful early in a stay if you want to understand the layout before using the bus system or linking parks. Go on a clear day; haze or rain can turn the tower into little more than an elevator ride.