Ah,
The Freedom Trail -- I forgot the name. And you can walk to the USS Constitution. A very nice walk (~1.5 mile) if it isn't too hot or too snowy. I meant it's not right downtown. (The last time I went was a very hot summer day, not a very good time to walk the grandparents around Boston and to the Constitution -- and not likely there will be a heatwave the beginning of March*.)
*But worst things have happened in Boston when it gets hot in the winter.