Near the river Miljacka at the Bentbaša street there is a so-called "Prvo Solarno Drvo" (First solar tree). It's a construction that really looks a bit like a tree with four solar panels on its branches. There is also an information sign with Bosnian text (sorry for the blurred photo) and a QR code that probably leads to the corresponding app that informs about the benefits of gaining energy from renewable sources.
A bench around the tree trunk is there to sit down and recharge the cell phone, tablet etc.