It is used on only handful of solemn liturgical occasions throughout the liturgical year. In brief, it is an ornamental covering and exposition throne made of silver and copper that covers the entirety of the high altar.
To give the point of comparison, here is a view of the high altar in its normal state:
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| Photo credit: Nicola de Grandi |
And here is the same altar once covered:
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| (Photo source) |
The various pieces seen here were not all created at one and the same time. The main part of the silver antependium that covers the front of the altar is thought to date from 1700-1710, crafted by the goldsmith Augusta Christian Winter, depicting the Madonna of the Rosary offering a rosary to St. Catherine of Siena and Fra Angelico. A closer look:
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| (Photo source) |
Various other Marian themes and titles, Sancta Dei Genetrix, Domus Aurea, etc. surround the central part of the frontal.
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| The coverings and tribuna where it is stored when not in use. Photo: Nicola de Grandi |
Some might notice that the frontal looks wider here immediately above than in the image preceding. This is because to either side of the ends of the original frontal were added two additional ornaments of silver and copper sometime in the 18th century.
To either side of the altar itself are two further pieces, decorated with cherubs, which were the work of the Milanese silversmith, Pietro Ceredi, dated to 1723. The first and second gradines are likewise his work, dated to the same time, while the third and final gradine is a 19th century addition.
The covering for the tabernacle and the framed altar cards are dated to the 18th century.
Sitting atop all of this is the Tribuna, used for Exposition of the Blessed Sacrament, crafted by the German silversmith, Hans Jakob Baur II. It is dated to 1677-79.
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| (Photo source) |
Finally, the candelabra and vases that were created for this arrangement were similarly dated to sometime in the 18th century:
All of this, of course, very much ties into the 'festal imperative' that manifests itself within so many aspects of Catholic liturgical life, from the traditional of red hangings to much grander ornament in general, be it more ornamental candlesticks, vestments or what not.
The purpose of this is twofold. One is to inspire and to emphasize the greater solemnity of the particular liturgical occasion to the worshipper; the other is that this is a manifestation of divine offering whereby honour and worship is offered to God through beauty and craftsmanship.
