Theoretical subjects, such as history, usually do not attract the interest of students and as a result educational games and serious games that use augmented reality (AR) are increasingly used as a means of supporting education. It is believed that these games can make the lesson more engaging and contribute to improving student performance. However, relevant research is limited. The present research presents the AR-enhanced serious game “Exploring Ancient Greece” that aims at supporting 10- to 14-year-old students in learning the history of Ancient Greece. It consists of three levels that include: a presentation of archaeological sites with AR that gives students the chance to explore places of historical interest; a trivia game that includes an AR presentation of a monument or piece of art somewhere in the physical surroundings of the students; and an escape room where the player is trapped in an archaeological site and tries to solve riddles to find the exit. To evaluate the game, an empirical study was conducted involving students between the ages of 10 and 14 who answered knowledge questions before and after playing the game, completed a questionnaire including questions based on the System Usability Scale (SUS), as well as questions for evaluating their experience, and answered oral questions. Based on the results of this study, students improved their knowledge of history, evaluated the game positively and stated that they prefer the use of serious games and AR in education.