Wasn't this answered somewhere else?
It is on Maimon Street at the corner of Juan Pablo Duarte. About a 15-20 minute ride from the airport. Anyone who knows Santiago knows where it is.
You need precise directions?
Airport-> exit straight ahead->airport road bends right_. you follow it and take the highway going west.
At the traffic light next to MERKAVEN, where you can see the Monument dead ahead, stay on the right. follow signs to Puerto Plata. Bear right, continue around in front of Hollywood theater. Stay in middle lane.
Go straight at the "metered" light, and 300 yards ahead you bear right and go down below the underpass. Stay in the left lane and turn left at the light. One block on your right hand side is the Metro Station.
Good luck.
HB