Set to break ground in May, Fairmont Heritage Place Mayakoba on Mexico’s Riviera Maya is offering one-twelfth fractional-ownership opportunities in 30 residences by the Miami-based firm SB Architects (St. Regis Bahia Beach Resort, Puerto Rico; Calistoga Ranch, Calif.; the Ritz-Carlton Kapalua, Hawaii). The interiors, by Los Angeles’s Rodrigo Vargas Design, will have a contemporary Mexican feel. Each of the residences will feature decor with such materials as limestone and dark woods, and will offer a full kitc…