The church’s three-axle, three-story western facade is in its current form since the 19th century. As a result of the great reconstruction by Frigyes Schulek, the original medieval carvings can be seen between the capitals of the portal in the central axis of the facade to this day. The rose window above the portal was also made on the basis of medieval fragments. It is an interesting fact that the finial of the triangular openwork pediment ornamented with arches bears the dates of the church’s exterior refurbishment: 1888, 1940, 1958 and 2009.

The western facade is dominated by the southern bell tower. The construction of the Gothic style tower built in 15th-century was finished by Matthias Corvinus in 1470. It was then that the king’s crowned royal coat-of-arms was placed onto the tower’s wall, thus it is called Matthias Tower. The church has three towers: the soaring Matthias Tower of the western facade, the stubbier Béla Tower with turrets, and a lightweight ridge turret at the junction of the transepts and the nave. The western towers’ square bases originate from the 13th century. The motives of Matthias Tower are dominated by the shapes of the 15th-century Gothic style, the serrated spire was built based on the plans of Frigyes Schulek in the 19th century.

On the southern facade three enormous lancet windows are situated between the two gates. The walled-up Bride Gate, which is the gate closer to the sanctuary, was opened at the time of the 19th-century restoration. Various sculpture fragments were used to wall up the gate built in the 1250s. To renovate the gate, Schulek used motives typical of 13th-century monuments, for example the decoration of the church of Ják had an impact on the architect. Schulek built an atrium in front of the Virgin Mary Gate, which is the gate closer to Matthias Tower. This protects the gate adorned with 15th-century Gothic carvings, the relief of which depicts Virgin Mary “falling asleep” and her assumption into heaven.

Frigyes Schulek found the walled-up Virgin Mary Gate during the 19th-century archaeological excavations and restoration. The Gate is one of the most important relics of Hungarian medieval architecture and architectural sculpture. The medieval double doorway portal built at the turn of the 14th and 15th centuries is decorated with a tympanum depicting Virgin Mary “falling asleep” and her assumption into heaven. It is an interesting fact that the carved scene does not depict the Virgin Mother lying in a bed, but saying her last prayer kneeling on a prie-dieu, while her soul arrives to Christ in the form of a crowned infant.

The church’s hall was created in basilica style in the 13th century. This means that two aisles of the three naves were lower, while the main nave got higher vaults. The main nave received direct light through the clerestory windows of the lateral aisles. The church’s current ceiling painting refers to this system – where the vaults were higher, the background of decorative painting is blue, while where the vaults were lower, the painting’s background is yellow. The current hall was created by lifting the aisles in the 14th-15th century.

In the middle of the relief depicting the crowned coat-of-arms of King Matthias, the Hunyadi family’s coat-of-arms with the raven is depicted. The carved and painted coat-of-arms originally adorned the side of the bell tower, in honor of the tower’s 15th-century renovation and the king who had had it built. Currently, a replica of the coat-of-arms can be seen on the tower’s wall. Frigyes Schulek placed the original relief inside the church in order to protect it against the weather.

The chapel dedicated to Our Lady of Loreto is located at the bottom of the bell tower, right from the main gate. The chapel’s rich ornamentation features symbols of the Virgin Mother. In the central panel of the triptych stands the 17th century replica of the statue of Our Lady of Loreto. The rose motif appearing on the windows and the gate bars of the church's most ornate chapel also symbolizes Mary.

Left from the main gate, at the base of Béla Tower the oldest stone carving in Budapest is located, which was found and restored in its original place. The capital, which was probably built towards the end of the church construction works in the 1260s, depicts two cowled figures pointing at a book. The special design of the window located at the tower base is an invention of Frigyes Schulek; this was his solution to the problem that the axis of symmetry of the external facade and the internal space does not coincide.

In the mural situated in the base of Béla Tower, Károly Lotz commemorated the defense against the Ottomans. In the triptych’s gable top appears Pope Callixtus III who ordered the noon bell ritual. In his papal bull he invited all Christian Europe to ask Mary’s intercession to stop the Ottoman army on the call of noon bells. In the two other pictures St. John Capistran leading the crusade army, and John Hunyadi listening to the bull’s promulgation are depicted.

The chapel was built in the 19th century with the financial support of the Zichy family. On the altar of the chapel the statue of Saint Emeric stands between the statues of Saint Stephen and Saint Gerard. Mihály Zichy painted the cardinal events of the eponymous saint’s life on the wings. On the chapel’s western wall murals depicting St. Francis of Assisi, patron saint of Ferenc Zichy, the donator, were painted.

On the chapel’s altar a special Holy Trinity representation, the Throne of Grace is depicted. The 15th-century triptych originates from the church of Felsőerdőfalva (today Stará Lesná, territory of Slovakia), and arrived in the Main Church of Buda Castle in the 19th century. In 1898 the tomb of King Béla III and his wife, Anne of Châtillon, was also placed in this chapel.

Saint Ladislaus Chapel is situated opposite the lamb window, next to the sanctuary. The important legends of the knight-king’s life and the miraculous events related to his name after his death were painted by Károly Lotz on the chapel’s walls. On the wall above the altar portraits of King Ladislaus, Béla III, who initiated the canonization, and Pope Celestin III, who canonized the saint are depicted. The replica of the Saint Ladislaus’ head reliquary preserved in Győr was also placed on the altar.

The church’s main altar stands in the central axis of the elongated polygonal sanctuary. On the historicist structure of the altar dedicated to the Virgin Mother both Romanesque and Gothic style elements can be discovered. The altar’s central figure is Virgin Mary appearing in a halo. The sanctuary’s windows are situated in two rows behind the altar. They depict saints and scenes related to the universal Church and the Holy Crown of Hungary.

The Holy Cross Chapel is located between the sanctuary and the Bride Gate. The sculptures of the calvary and the pieta decorating the altar were carved by Ferenc Mikula. In the sitting alcoves Arma Christi, i.e. the Instruments of the Passion, and the symbols of the Eucharist appear. The wall behind the altar is decorated by tendril and leafy floral ornaments, similar to the motives appearing on the window frames and in the main sanctuary.

The Saint Stephen Chapel is connected to the church as a separate chapel on the northern side. The neo-Gothic chapel was built on the site of the Garai family’s burial chapel, and was designed to provide place for the Holy Right Hand of St. Stephen. On its windows and in itsmurals miraculous events of Hungarian saints’ lives and related to the Holy Right Hand of St. Stephen are depicted. In the end, the Holy Right was never located in the chapel, therefore, the chapel was named after the king related to the relic.

The enormous lancet windows situated on the southern wall tell about the lives of three female saints. The central window depicts scenes from the life of Virgin Mary, while the other two depict the cardinal events of St. Margaret’s and St. Elisabeth’s lives and legends. The two Hungarian princesses are closely related to King Béla IV, the founder of the church, as Margaret was the King’s daughter, and Elisabeth was his sister.

The church had a music ensemble already at the time of Matthias' reign. The choir and orchestra serving here had such famous choir directors as Viktor Sugár or Lajos Bárdos. The church’s most important musical instrument, which can still be found here, was made in 1909 with the financial support of Franz Joseph; therefore, it is also called the “King’s organ”. The instrument is Budapest’s largest organ, and can be sounded together with the choir organ. It has altogether 7771 pipes, 111 stops and four consoles.

In the history of the church it occurred several times that flags seized in victorious military campaigns were exhibited in the Main Church of Buda Castle. In 1444, after John Hunyadi’s Balkan campaign the seized flags of the enemy were also exhibited. The flags currently visible in the church were part of the decoration of the coronation in 1867. The flags of historical Hungary’s provinces were certainly not used in the church but rather on a representative route in the city, considering that the royal couple’s name and the date of the coronation are not marked on them. They became part of the church’s collection after the coronation ceremony. Currently, reproductions of the original flags can be seen.

Following the coronation in 1867, the church became a distinguished building, therefore, after the 19th-century restoration a separated space was created for the royal family. An elegant, hexagonal neo-Gothic staircase with openwork handrails leads to the royal oratory facing towards the sanctuary.

The chapel of the Hungarian Association of the Order of Malta was created on the small organ loft located above the chapter sacristy. The Order was reformed in 1928 but they established a chapel in the Coronation Church of Buda already in 1927 where they could meet and pray together on festive occasions. The shields depicting the family crest of deceased knights were placed on the walls of the chapel and the corridors leading to it.

The chambers above the northern side chapels currently provide venue for the museum’s exhibitions. Béla Tower and Béla Chambers were named after Béla IV, Hungarian king and founder of the church.