While you're at Copley Square, take a minute to visit the tall building. The John Hancock Tower reflects the older buildings around it. The tallest building in Boston, it has a sightseeing deck and museum on its top floor.
If you're more into bargain basements and blue light specials, take the Red Line to Downtown Crossing and visit Filene's Basement, the mother of all bargain basements.
There, you will make your way through mile-long racks of designer clothes, all priced to please.
For the artistically inclined, the Museum of fine Arts (MFA) at the Museum T stop on the Green Line houses a comprehensive assortment of international art.
The museum boasts an impressive collection of impressionist paintings, including 35 works by Claude Monet. To save money, be sure to stop by Wednesdays from 4 to 9:45 p.m., when admission is free.
On your way to the MFA, take an interesting detour at the world headquarter of the First Church of Christ Scientist (T: Symphony, Green Line). The nineteenth century Mother Church is to the Christian Scientists what St. Peter's in Rome is to Catholics.
And though not as massive as St. Peter's, this church seats a huge congregation and boasts a thunderous organ and requires an elevator to reach its chapel.
Walk beside the church and catch a breathtaking glimpse of an immense reflecting pool. Also try to visit the "Mapparium," a huge glass globe you can walk inside.
Another favorite tourist spot is Chinatown (T: Orange Line to Chinatown). A good time to visit the area is on a bright, i.e. sage, weekend afternoon when you can enjoy dim sum in one of the numerous Chinese restaurants, and avoid much of the crime that has plagued the area in the past.
The list of things to see and do in Boston goes on and on. Catch a Red Sox game at historic Fenway Park, feature in the movie Field of Dreams (T: Kenmore, Green Line).
Watch an Omnimax film at the Museum of Science (T: science park, Green Line). Or make a visit to the John F. Kennedy Presidential Library (T: JFK/UMass, Red Line).
But whatever you do, don't forget to send Grandpa Bob a postcard.