This is a book about doors and thresholds: about entrances to prehistoric sanctuaries, Egyptian, Greek, and Roman temples, medieval cathedrals, fortresses, palaces, and villas. It is about what makes them special — the symbolic meaning their creators invested in them. Each door signifies a passage, and a threshold is a certain boundary between two realities, the border of two worlds and two states. Doors are inextricably linked with concepts of change and evolution, and sometimes serve as a connecting thread between dream and reality, light and shadow, ignorance and wisdom. Oscar Martinez invites the reader on a journey: from the House of the Vettii in Pompeii to the Dolmen of Menga and the Abbey of Sainte-Foy; from Hadrian's Pantheon to the Arch of Titus; from the burial complex of Ramses III to St. Mark's Cathedral; from the Comares Palace in the Alhambra to the Bauhaus building in Dessau; from the Güell Estate in Barcelona to Castel Nuovo in Naples; from the Quinta da Regaleira in Portugal to the Secession House in Vienna... This book of essays opens doors to the history and culture of different eras. Readers who have already passed through these doors may see them with new eyes. And those who are not yet familiar with them will discover their timeless grandeur.