Although the people living in Sundbyberg don't agree, Sundbyberg is a suburb to Stockholm. They would rather talk about Sundbybergs Stad, Sundbyberg City. Sundbyberg is a cozy place, looking like a small town on the country side. Still, it is only a ten minutes ride by subway to get to T-centralen, the Stockholm railway station.
One of my favorite things about Sundbyberg is its Coffee roasters. Sometimes when the wind is right you get a nice smell of newly roasted coffee when you step out the door at morning.
If you are to spend one day in Sundbyberg I would recommend you to go strolling by the small lake Lötsjön, where you can feed the birds and have an ice-cream at Gröna Stugan.