Directly across the road from the palace. Once you cross the road the loop around the palace is approx 5k. The walkway around the palace is perhaps 2 meters wide so lots of room and no traffic to worry about. Next door to the hotel was Tokyo FM, they seemed to have a sign outside advertising "JOGLIS" the Hanzomon runners club. However I didn't try it.
The Patio restaurant had an "American" breakfast for Yen 1200 ( approx 10 Euro ). It consists of a small salad, tea or coffee, orange juice, eggs, ham and toast. Very nice. At night the Patio restaurant serves Japanese and "American" food. I had Pizza and beer very nice.
The room was small but very comfortable. I had an excellent view from the 14th floor out over the city. Room cost was 11,000 Yen / night including breakfast which seems good for such a nice hotel in a central location. Honzomon station is just around the corner and you need 1 change to get to Tokyo station on the far side of the palace. The area seemed very safe with lots of police in evidence due to the number of embassies and government ministries in the area. Had a nice pint of Guinness in the "Three Thread" English bar about a mile away.More