SUBJECT LINE: Fifty Boston-area summer recreation sites

Boston by Foot offers weekly excursions of subterranean Boston, focusing on the city's underwater tunnels, historic subway system, and engineering feats. Meet at Faneuil Hall in front of the statue of Sam Adams. $10, $8 children; 617-367-2345. . . . The Big Dig may be a nuisance, but it has provided terrific tour opportunities. ................
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