21 November - The Presentation of Our Lady in the Temple

Which is today's feast in the Roman calendar, the N.O. calendar and the Ordinariate calendar.

Background on the history of the feast here in the excellent New Liturgical Movement blog.

The collect from the DW Missal:

Almighty and everlasting God, who by the overshadowing of the Holy Ghost didst prepare the body and soul of the glorious Virgin Mother Mary to be a dwelling-place for thy Son:  grant that we who rejoice in her Presentation may at her tender intercession be kept unspotted, and made a pure temple for his dwelling; who liveth and reigneth with thee, in the unity of the Holy Ghost, ever one God, world without end. Amen.