Denver International Airport (DEN) sits inside the Aurora city limits, on the far north-eastern edge of town — most international visitors land essentially in Aurora already. Rental cars, ride-share, and the RTD A Line commuter train all run from the airport to Union Station in downtown Denver in about 35 minutes; from there the R Line light rail runs back south into Aurora and reaches the medical campus, the courthouse, and downtown.
Driving from Denver, Aurora is fifteen to thirty minutes east along Colfax Avenue, 6th Avenue, or Interstate 225. The city has no central downtown to navigate to — pick the specific neighbourhood you want and use a GPS.