Originally, a church from the 13th century was located here that got destroyed during the Hussite invasion. The present temple received its architectural form in 1482–1492, which is confirmed by the dates carved on the elevation. Perhaps, a part of the nearby church of St Dorothy from 1194 was incorporated into the building, as is suggested by the asymmetrical location of the body relative to the presbytery. The new temple received forms typical of the late Gothic architecture of Saxony and Lusatia, which indicates the origin of the workshop that carried out the work. In the early 16th century, a number of chapels were added from the south.
In 1524–1640 the temple was used by Protestants. After a fire in 1642, it was rebuilt in 1655–1692. For the last three years, an Italian builder, Giulio Simonetti, was in charge of the work. Under his supervision, vaults of the main nave were built and the temple interior was baroqueized. The neo-Gothic tower dome was made in 1843.
In the 18th century, the temple became an important pilgrimage site due to the Holy Cross relics being placed here. On 27 June 2004, the temple was raised to the rank of Marian Shrine, and on 7 October 2012, it received the status of Minor Basilica of the Legnica Diocese, making it one of the three most important temples in the region.
The southern elevation is adorned with an entrance portal with statues of St Sebastian and St Roch by Georg Leonard Weber taken in the 19th century from the demolished Upper Gate, epitaph plaque of Kaspar Kirchner, an outstanding thinker and poet of the Renaissance, epitaph plaque of Thomas Heinsius (†1571) with a scene depicting the sacrifice of Isaac (according to some researchers, the view of the city presented here is the oldest preserved image of Bolesławiec) and a sundial made by master R. Munzky in 1907 with a Latin poem: „Hora fugit, Mors venit, Umbra transit, Lux manet” (Time flies, death comes, shadow passes, light remains).
On the western elevation, one can see the west portal with statues of St Hedwig, Mother of God, St Joseph and St John of Nepomuk by G.L. Weber taken from the city gates, a bas-relief depicting the Holy Trinity, with the date 1533, also brought to its present location from the Upper Gate and the date 1516 from the time the church was remodelled.
The northern elevation features an embedded epitaph plaque of the potter Matthes These (†1625) and the date 1492 on the window in the northern wall of the tower that marks the completion of the church construction.
On the eastern elevation, covering the presbytery, one can see an inscription in the Gothic minuscule: „Anno Domini m ° cccc ° lxxxii °” (in the year of our Lord 1482) indicating the beginning of the church construction and an image of the Silesian Eagle; below, there is an epitaph plaque of Esther Praller, and in the basement part the foundation stone with four tau crosses forming the so-called Krueckenkreuz is embedded.
In the 18th century, the church received rich, baroque furnishings. The extended main altar with the Assumption of the Blessed Virgin Mary scene in the central part was erected in 1725 after G.L. Weber’s design. It is also adorned with numerous figures of saints: Peter and Paul, Augustine and Nicholas, Stephen and Lawrence, Wenceslaus and Leopold, placed in front of columns, the Holy Trinity image placed on the top, surrounded by angels and allegorical figures symbolizing Faith, Hope and Love, and statues of St Ludmila and St Hedwig on sides.
The temple has four side chapels: of the Holy Cross, St Barbara, St Catherine of Alexandria and St Alexius. Also noteworthy is the decorative vault of the sotocoro associated with Roskopf’s workshop.
The furnishing is complemented by numerous altars, including the altar of the Immaculate Conception (ca. 1722, today: of Our Lady) by the painter Jeremias Joseph Knechtel of Legnica as well as the pulpit and paintings, incl. „Crucifixion” by G.W. Neunherz. On the crowning cornices, there are figures of 12 apostles attributed to G. Simonetti’s workshop. Above the chancel arch, the Scene of the Annunciation is visible.