Chennai is the nearest airport and if you wish to take a tour to Mahabalipuram then drop into the Chennai Airport. Chennai is 45 km from Mahabalipuram.
The nearest railway station is Chennai Railway Station which is at a distance of 45 kms. Chengalpattu is another station which is at a distance of 29kms and is well connected with other cities in Tamil Nadu. However Chennai remains the major railway station to reach Mahabalipuram.