Princess Leonor of Asturias swapped her military uniform for jeans as she began life as a student at the Carlos III University of Madrid today.The heir to the Spanish throne was all smiles as she posed for photographs on her first day of university, where she will embark on a four-year degree in Political Science.The eldest daughter of King Felipe and Queen Letizia, who completed her military training in July, was dressed casually in a short-sleeved, white blouse, dark-wash jeans and trainers as she stepped out at the Getafe campus near the capital.With her blonde hair styled into a French braid, she accessorised with a large, black leather bag with silver hardware and a simple necklace.At the Spanish university, Leonor will study courses in humanities, economics, sociology, history and international relations as she prepares for her future as queen, a statement from the palace said.'The Princess of Asturias has concluded her first day of university,' the royal household said in a statement alongside a video of Leonor on campus. She attended classes in Legal Theory, Research Methodology in Social Sciences, and Fundamentals of Political Science in addition to a welcome session organised by the program director Gema García Albacete. It comes after Leonor, 20, received the title of Adoptive Daughter of San Javier, alongside the Gold Medal of the Town, to mark the conclusion of her intensive Air Force training in San Javier. Princess Leonor of Asturias swapped her military uniform for jeans as she began life as a student at the Carlos III University of Madrid todayAs she is the heir to the throne, Leonor will one day take the title of Commander in Chief of the armed forces and therefore was required to spend time in each section of defence.The award acknowledged her commitment and connection to Spain’s armed forces and marked an important moment in her royal journey.The Navy Merit Grand Cross is a high-level military decoration awarded for distinguished service within the Navy.Leonor's mother Queen Letizia and younger sister Princess Sofia beamed as they watched the ceremony.The royal started her aeronautical training after arriving in San Javier last September.A message written in the Academy's Book of Honour by Leonor said: 'Today I begin the third stage of my military training at this General Air and Space Academy. I look forward with enthusiasm to this course, during which I will have the opportunity to begin my aeronautical training and, alongside my classmates, learn the practical and theoretical aspects of military aviation.'The Princess is following in the footsteps of her father King Felipe, as well as her grandfather Juan Carlos, who all attended military training with all three of the armed services in the country.Before she started her three-year training, Leonor revealed her enthusiasm for becoming a cadet at the Princesa de Girona Foundation award ceremony in Girona last year. The eldest daughter of King Felipe and Queen Letizia, who completed her military training last month, was dressed casually in a short-sleeved, white blouse and dark-wash jeans as she stepped out at the Getafe campus near the capital Excited onlookers took photos of the Spanish heir to the throne as she embarked on a four-year degree in Political Science Leonor began her studies today alongside 3,000 other students at the Getafe campus, a statement on the Spanish Royal Family's Instagram read She said at the time: 'I have just finished high school and I am about to start a new stage with a period of military training.'I am happy because I know how much the Spanish value our armed forces... it is an important moment in my life and I feel very excited and determined to continue learning and giving my best effort.'Ahead of starting her university degree, Leonor and her younger sister Infanta Sofia attended the annual Marivent Palace reception in Majorca alongside the Spanish King and Queen. It marked only the second time the two young royals, aged 20 and 19, have attended the prestigious event – and the sisters were captured arriving arm-in-arm with their 87-year-old grandmother, Queen Sofia, at the Palace.Embracing the bold and bright colour scheme, Queen Sofia opted for a silk floral Alejandro de Miguel caftan over a burgundy dress, which she paired with a geometric necklace and Isabel Gurach brooch to accessorise.Her granddaughters arrived in style – with Leonor opting to wear a two-piece orange and red ensemble by Spanish brand Thinking Mu.Leonor wore the top to a Bad Bunny concert in Madrid earlier this summer. This time, she accessorised the look with gold sandals and a gold arm cuff.Her sister, meanwhile, stepped out in a pink, blue and white floral Libelula maxi dress by Italian brand Momoni, which she finished with a gold belt.Queen Letizia looked as regal as ever in a cream midi dress with stylish coordinated sandals, while the King sported a polished look in a tailored blue shirt and dark trousers.