Glouster
In New Hampshire.. the Mount Monadnock?
Mt Agameticus?
Temple Mountain in NH?
Is it Wachusett Mountain or Watatic Mntn?
Ward Reservation
Too far West but thanks for the ideas. Trying to find some easier hikes this year, like the one I was on.Pratt Mountain in New Ipswich? Or Kidder Mtn.?
The observation tower on South Mountain?
Did some digging with the clues provided and I am fairly sure you were at South Uncanoonuc Mountain in Goffstown.
I am very impressed! I was actually looking at that "mountain" again yesterday while walking through Manchester. It's very obvious looming over the area with an antenna farm on top. You can't quite get to the exact summit, but there's a couple paths that form a full loop around it, with 3 key viewpoints. One you can see Boston to Wachusett, one you look down on Manchester, and one you can see W/NW including Mt Monadnock and Mt Kearsarge (2 of my favorite/standard hikes).