Andrea Casiraghi, the son of Princess Caroline of Monaco, will marry Tatiana Santo Domingo, the granddaughter of late Colombian mogul Julio Santo Domingo, in Monaco today. We’re told the couple will tie the knot in a private civil ceremony in front of a few friends and relatives. A more lavish affair is planned to celebrate their union in Gstaad this coming winter. Guests expected at this weekend’s ceremony in the principality include Prince Albert and Princess Charlene, and Tatiana’s close friends including Andrea’s sister Charlotte Casiraghi, Margherita Missoni of the renowned Italian fashion family and Greek shipping heiress Eugenie Niarchos.