One church, at least, in every new place I visit. Dwarfed by the majestic doors of St. Peter's Basilica

Maundy Thursday is Visita Iglesia. It’s a Lenten tradition for the Filipino Catholics to reflect on the Passion of Christ. Perhaps to this day many still ask how many churches one really has to visit. Two numbers are commonly practiced—seven and 14—and have become a tradition. Seven represent the key locations, or the “stops,” related to the suffering of Jesus, and 14 represent the Stations of the Cross.

Just as Roman Catholics abide by their essential duties, I have my own travel rules, like visiting at least one church in every new place I visit. If the trip falls on Holy Week, then this tourist-devout Catholic is in heaven's favor.

The Old World cathedrals are the most captivating because they double as museums. On my first visit to these European destinations, here are seven of my favorite cathedrals—holy houses that I would love to revisit for Visita Iglesia on one Maundy Thursday, if that is even possible.

Basilica de la Sagrada Familia, Barcelona, Spain (v. 2003). It was the most breathtaking sight of my first trip to Barcelona. That year, I was told that the Antonio Gaudí-designed basilica, which began construction in 1882, would take a couple more lifetimes to complete. However, modern technology hastens the construction process, moving the target completion of Sagrada Familia—structural and interior—to within 2030-2035.

The basilica is a UNESCO World Heritage Site and currently the world's tallest church at 172.5 meters at its highest point. It is renowned for its unique features, including 18 symbolic spindle-shaped towers; a breathtaking forest-like interior with support columns that branch out like trees; rose windows that flood the interior with a kaleidoscope of light throughout the day; and three intricately designed nature-inspired facades—the Nativity, Passion, and Glory.

St. Vitus Cathedral, Prague, Czech Republic (v. 2014). A cathedral founded to house the relics of St. Vitus, everything about the metropolitan cathedral is grand, from its history to its imperial architecture and interior design to the breathtaking view it presents. It is the largest and most important church in the Czech Republic, where Bohemian kings and Holy Roman Emperors are entombed. Located at the prime address of the Prague Castle grounds on the west bank of the Vltava River, the magnificent church is a masterpiece of Gothic and Neo-Gothic architecture that dominates the city skyline. Reciprocally, from the cathedral’s Great South Tower, accessed via a 287-step staircase, a panoramic view of the entire city is framed by the lofty windows.

The interior with soaring vaulted ceilings is lit up with a tapestry of colors through the intricate stained glass windows, including the Art Nouveau masterpiece by renowned Czech artist Alfons Mucha, depicting the lives of Saints Cyril and Methodius.

Take a peek at the St. Wenceslas Chapel. Almost jewelry box-like, the rib-vaulted room is embellished with 1,300 semi-precious stones and Gothic frescoes of the Passion of the Christ and the life of St. Wenceslas, making it precious enough to cradle the relics of the saint. In one corner of the chapel is a door with seven locks. It leads to the Crown Chamber housing the Czech crown jewels.

St. Peter’s Basilica, Vatican City, Italy (v. 2004). The burial site of the first pope, St. Peter, is one of the holiest Catholic shrines and the largest church (by interior measure) in the world.

A Renaissance masterpiece, the shrine is like a museum with the most impressive creations by preeminent masters of the art world. From the approach to entry, every step draws gasps of amazement. From the multitude of impressive features, these may be the most memorable: the monumental elliptical forecourt of St. Peter’s Square designed by Bernini; the subterranean Vatican grottoes and necropolis holding the papal tombs, including St. Peter’s; the world-famous marble sculpture by Michelangelo, the Pieta; and drawing one’s focus to the central features of the church situated above the burial place of St. Peter—the magnificent dome by Michelangelo, the world’s tallest dome, and Bernini’s Baldachin, a massive bronze canopy over the Papal Altar.

Basilica di Santa Maria del Fiore, Florence, Italy (v. 2006). The fourth largest church in the world, the Florence Cathedral, naturally dominates the Firenze skyline. It’s one of Italy’s most photographed churches, and for good reason—the cathedral is artistically rich. It starts with the breathtaking 19th-century neo-Gothic-designed façade—a collective work of several artists finally reaching completion in 1887—featuring white, green, and red marble in its construction.

Through the three intricately designed bronze doors, discover within the interior what made the cathedral a symbol of Renaissance engineering. Over the central crossing, where the nave and transept intersect, is a massive octagonal drum referred to as Brunelleschi’s Dome. It is the largest brick dome ever built, an architectural feat. The interior of the dome is as impressive, with a massive fresco of the Last Judgment decorating the dome’s expansive surface.

The cathedral complex, composed of the Florence Cathedral, Florence Baptistry, and Giotto’s Campanile, is inscribed as a UNESCO World Heritage Site.

Duomo di Siena, Siena, Italy (v. 2006). It’s as stunning, historic, architecturally innovative, and art-filled as the Florence Cathedral. Designed in the Tuscan Romanesque style, the unique exterior and interior of the Siena Cathedral are constructed of black and white marble in alternating stripes, colors that symbolize Siena, which is linked to the city’s legendary founders.

Truly a magnificent creation is the floor’s design. Taking over 600 years to complete, 40 artists created 56 etched and inlaid panels for the cruciform floor plan. Resting on it are eye-catchers, including the pulpit carved from Carrara marble by Nicola, considered the founder of modern sculpture. On the left nave is the 1482 Libreria Piccolomini, housing a large collection of illuminated choir books and vibrant Pinturicchio frescoes illustrating the life of Pope Pius II.

More prominent artists of the time, like Bernini, Donatello, Ghiberti, and others, took part in the completion and adornment of the cathedral.

Notre-Dame de Paris, Paris, France (v. 2003). Located by Point Zero in Central Paris, the 12th-century medieval Catholic cathedral is one of the finest examples of French Gothic architecture. Its most important innovation during the era was the introduction of the flying buttress seen at the rear end, while the lofty spires, twin bell towers, and three massive rose windows add to the distinguishable features of the cathedral.

Equally as remarkable are the lavish decorations that wrap the structure—artful appointments that vividly relate biblical stories, medieval science, and philosophy, from The Last Judgment and the gallery of kings to the lives of saints, and from gargoyles and chimeras to alchemy symbols.

Under the soaring vaulted ceiling of the interiors are the most treasured articles of Notre Dame, priceless religious relics including the Crown of Thorns, a piece of the True Cross, and a nail from the Crucifixion, along with the 17th-century “May” paintings.

Basilica de Santa María del Coro, San Sebastian, Spain (v.2006). It’s difficult to ignore the grand 18th-century Baroque façade of the basilica in its strategic location at the end of the narrow Calle Mayor in San Sebastián's Parte Vieja (Old Town). The elaborate Rococo and Baroque ornamentation of the basilica’s concave portal, with a tortured figure of Saint Sebastian above it and framed by two bell towers, highly contrasts the look of the contemporary urban structures that line the street where pintxo hopping is the lifestyle.

More sober and restrained than its ornate exterior, the interior of the 1774-completed minor basilica stays true to the Baroque style but with the incorporation of Neoclassical and Gothic architectural elements.

Under the ribbed vaults are the basilica’s treasures: a romantic instrument in a Baroque case created by Cavaillé-Coll, a renowned French organ maker; a large 1819 painting of the martyred patron saint, Saint Sebastian, by Luis Boccia; century-old paintings and statues housed in alcoves; and, serving as the interior’s highlight, the 18th-century gilded main altarpiece.

However, the basilica’s most treasured piece may come unexpectedly. It is a 16-inch dark wooden statue of the Virgin Mary from the 15th or 16th century. It’s believed to be a miraculous piece.

In your trips abroad, which among the cathedrals and churches you have visited impressed you most?