Source: ST:M
The airlock doors are situated lower down the "spine" than the sensor platform and above the aft-firing photon torpedo launchers.
Paramount deliberately designed the docking port/airlock doors as copies of the studio stage 9 shuttlebay doors, and therefore also the holodeck doors, in case they ever had to build a piece of the exterior hull.
Source: ST:M
Below the docking port/airlock doors are twin photon torpedo launchers. This Starfleet design was first seen on USS Voyager.