The Radar: Top Baseball Stadiums, National Train Day, Free Paris Walking Tours

• Catch a game (or a fly ball) this summer at Boston’s Fenway Park, the oldest baseball stadium in the country and number four on the list of top 10 ballparks to visit.  [Away.com]

• May 7th is National Train Day and Amtrak is celebrating 40 years of service by letting kids ride the rails for free for 40 days. Book between May 1 and 6 and kids travel free on trips taken between May 1 and June 9. Get your kids excited about their next train trip at Amtrak’s online Train Depot, plus check out the list of nationwide events going on to celebrate the anniversary. [Amtrak]

• Stretch your legs without stretching your wallet on one of these free walking tours of Paris. [EuroCheapo]

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Photo: Courtney Flynn/My Shot