alcaldía
city hall
alcalde
mayor
+
-ía
place or institution related to
Alcaldía means city hall and can be thought of as the place related to1 (-ía1) the mayor0 (alcalde0).
noun
- city hallMayor's office or city hallTengo que ir a la alcaldía para renovar mi licencia. // I have to go to the city hall to renew my license.