National Realty & Development Corp. broke ground this week on its $100 million waterfront residential development in New Rochelle, the former site of Beckwith Pointe on the southern tip of Davenport Neck. WatermarkPointe, a 72-unit luxury project at Davenport Avenue on the Long Island Sound is being developed by National Realty & Development Corp. According to the development’s website, the property will have nine buildings with eight residences per building featuring a mix of two-bedroom and three-bedroom condos. Amenities include a waterfront clubhouse, fitness center and outdoor pool overlooking the beach. Beckwith Pointe was a 30-year-old beach club and catering hall.