Portals are points of interest where XM ingresses or enters our world. They often manifest as public artwork or sites of cultural significance, such as statues, monuments, murals, and other displays of human achievement.
Protip: Public university campuses, arts districts, and public parks are often rich with Portal activity. Visit the Intel Map at https://intel.ingress.com to view Portals in your area.
If there are no Portals visible on your Map screen, then your Scanner will attempt to show you what direction or heading to travel towards to visit the closest Portal nearby.