Rumor has it caliber runners like Utta Pippig and Bill Rodgers are sprinting to check in to the new Charlesmark Hotel, located on the finish line of the April 15 Boston Marathon. Don’t let the Back Bay hotel’s 19th-century facade fool you; it masks a millennial spirit indoors. After gutting an 1886 mansion down to its joists, Charlesmark’s owners installed 33 modern rooms with platform beds, marble bathrooms, and high-tech entertainment systems. In addition to the marathon mark, views from the second-floor lobby take in the historic Boston Public Library across the street. From $135. (617) 247-1212, www.charlesmarkhotel.com