Lalbagh Botanical Garden was built during the late 1700s and functions as both a botanical garden and park for social gatherings. Various cultural events like flower shows and live band performances take place here fairly frequently, and it's a great place to relax and appreciate nature. I've only been here a few times, but every time I have been here, I've left with a new appreciation of some kind of plant I was not aware of previously.
The Visvesvaraya Industrial and Technological Museum (I will call it VITM for convenience) is a place I enjoyed going to as a kid. They have a lot of really interesting models of old planes and trains, live shows, and other demonstrations of scientific phenomena. It's very engineering-focused, with entire halls dedicated to engine models and space technology. They have some really cool plane models outside around the building that I used to stare at whenever I passed by.
My family is really into hiking, so we went to Nandi Hills a lot when I was growing up. There were a few times when I'd have to wake up outrageously early so we could get there in time to watch the sunrise. I couldn't really appreciate it as a kid because I was too busy being upset about my lack of sleep, but I'm sure the view was great in-person considering we went back more than once. There was a restaurant nearby that served a really good breakfast that was the highlight of my trip when we went there, but I can't remember the place's name.