The building, as it exists today, is a mixture of several architectural styles – Romanesque, Gothic, Renaissance, Baroque and Historicist. According to chronicle accounts and modern research, the original church was built in the 10th century. Along with the ossuary in Sedlec near Kutná Hora, the Mělník ossuary located in the church crypt ranks among the largest in Bohemia. It was created in the 1530s and houses the remains of about ten to fifteen thousand people. It was organised into its present form by professor Jindřich Matiegka. The ephemeral nature of life is brought into focus using images constructed out of bones and skulls – crosses, anchors and hearts, which is to say the symbols of faith, hope and love.