Imperial Palace Gates and Subway Stop
 

If I understand correctly there are 3 gates to the Imperial Palace Garden. Heading over from Shinjuku what would be the best stop to put us in the middle?Tokyo Station and walk over? Or do we hop back on the subway to get to he other section of the Garden?
Chidorigafuchi Memorial Garden, the East Garden and Sakurada-mon(gate of the field of cherry trees) are on top of our list to see while visiting the Imperial Palace.
Thanks in advance....

Nijubashi-Mae (Chiyoda-Line/Green)is the subway stop I usally use. From Tokyo Station, perhaps you will walk twice more.

Are you visiting the Imperial Palace - Garden with reservation? Otherwise, probably you cannot visit inside the place.

We walked from Tokyo Station, both ways. Here's information about the palace grounds, and a link to the website to make application for a visit inside the palace:
http://www.japan-guide.com/e/e3017.html

Thanks! Just interested in the garden not really inside.