St. Augustine has no commercial airport. The nearest airports are Jacksonville International Airport (JAX), about 50 miles north, and Daytona Beach International Airport (DAB), about 60 miles south. Jacksonville is the more useful option — it has better flight connections and the drive to St. Augustine takes under an hour on I-95.
By car, St. Augustine sits on I-95 at exits 305–311. From Jacksonville take I-95 south; from Daytona take I-95 north. The historic district is not well-served by parking — the main lots near the visitors center fill up quickly on weekends. Arrive early or park in the free lot by the visitors center and walk in.
There is no practical Amtrak or Greyhound service to St. Augustine. The nearest Amtrak station is in Jacksonville.