Walking the The Freedom Trail is a must when visiting Boston and there is an app for that. Download "Freedom Trail Walking Tour" for free and walk the trail at your own pace. Maps can be picked up at the State House.
Samuel Adams Oktoberfest happens to be one of my favorite beers, so when in Massachusetts a visit to the Samuel Adams Brewery should be on your list. I strongly encourage reserving a spot online as these tours are popular. Take the T-train Orange line to the Stony Brook stop and the brewery is two blocks away. Like all good brewery tours there is a tasting at the end but one of my favorite features of this tasting is they test flavors at this location so some of the beer you will find is not sold in stores. Cheers.
Take a stroll through the Beacon Hill neighborhood to see beautiful old colonial homes, cobblestone streets, and do a little boutique shopping.