Granite and concrete blocks are installed as part of Operational Projects as hardening in order to provide safety for pedestrians. Many granite blocks have been repurposed from bridge rehabilitation projects across the City. These blocks are a sustainable solution that integrates seamlessly into New York City’s urban environment. NYC DOT also purchases new blocks when needed.
The rectangle ones look a bit odd, but the ones with natural looking shapes look quite nice imo.
Also fun fact the name of the colour of my phones backplate is based on a Finnish town sharing your username, Inari blue.