Stepping inside the portico of this mammoth church, you'll be awestruck by its sheer scale and history. The colossal central doors, cast in bronze, once adorned the entrance of the Curia Iulia, the ancient senate house in the Roman Forum. You'll also have the opportunity to see the Holy Doors - only open in the event of a Jubilee or Holy Year, every 25 years. Your guide will explain the rich theological meaning and historical significance of the Jubilee - an important year of pilgrimage for Catholics worldwide. Inside the Basilica, you'll be greeted by Borromini's soaring Baroque genius, who redesigned the interior in the 17th Century. Traces of the ancient Basilica remain, however; follow your guide, who will reveal medieval frescos by Giotto and guide you through the complex meaning of the iconography of the apse mosaics. You'll also discover more about the history of the early Church in Rome and learn how Saints Peter and Paul's relics came to rest here.

Join your guide and explore more of this once-vast and ancient complex. First, you'll visit the Holy Steps (Scala Santa), a set of 28 marble steps brought to Rome by St. Helen, Constanine's mother. According to tradition, these are the steps that Christ climbed up the palace of Pontius Pilate during the Passion. Even today, they are a place of solemn pilgrimage for the devout. At the top lies the Sancta Santorum (Holy of Holies). Long before the Sistine Chapel, this was the pope's private chapel. It once held some of the most precious relics in the Christian world. Even today, it is the home of the mysterious "acheiropoieton," an ancient image of Christ said to have been painted by angels (visitable on a private excursion).

Then, visit the Lateran Baptistry, the legendary site of Constantine's baptism. Its octagonal shape inspired other baptistries around Italy and Europe, including the famous Baptistry of Florence. Why were early baptistries eight-sided buildings? And why were they housed in separate buildings? Your local guide will answer these questions and more. Before leaving the Lateran, take a moment to admire the enormous Lateran Obelisk, the tallest standing obelisk in the world today. Discover how these ancient Egyptian monuments were recycled, first by the Romans and later by the Christian Church.

Now, we embark on our own pilgrimage, down via Merulana, a road laid out in the 16th Century to help visitors to Rome on their pilgrimage. You can see our next destination at the end of this straight avenue. Along the way, we'll make a stop at one of Rome's most famous bakeries—Panella. In business since 1929, Panella has kept Romans on the go with its excellent coffee and sweet treats for years. Try the traditional Roman maritozzi, sweet yeasted buns filled with freshly whipped cream—just what a weary pilgrim needs! The view over the Auditorium of Mecenate reminds us of this area's importance, even in the ancient world.

Finally, we arrive on the highest of Rome's seven hills, the Esquiline, home to the largest church dedicated to the Virgin Mary in Rome. The story of this Basilica lies somewhere between history and legend, but of all of Rome's papal basilicas, Santa Maria Maggiore feels the most ancient when you step inside. In addition to its revered Holy Door, this Basilica boasts ancient Cosmatesque floors and a ceiling adorned with some of the first gold from the New World. Among various relics and ancient mosaics, you'll also find another Sistine Chapel (the resting place of Sixtus V), the grave of the Baroque great Gian Lorenzo Bernini, and a sacred image of the Virgin, Salus Populi Romani—an ancient image that was said to have saved the people of Rome in the 6th Century AD. End your personal pilgrimage at the obelisk of Santa Maria Maggiore, an ancient gem just steps from Rome's main train station and the fashionable Monti district.