Catholics believe that Christ is truly present in the consecrated bread of the Mass, and adoration is time spent in that presence. The U.S. bishops describe it as an extension of the adoration that takes place in every Mass, and note that the Church has a rite for it, the Rite of Eucharistic Exposition and Benediction. Exposition, they say, flows from the sacrifice of the Mass and serves to deepen hunger for Communion with Christ and the rest of the Church. The rite ends with the ordained minister blessing the people with the Blessed Sacrament. A "holy hour" is simply the tradition of spending an hour this way.
What people actually do is a matter of custom. On entering, Catholics usually genuflect or bow toward the Host, then kneel or sit. The room is kept silent. Some gaze and say nothing; others pray the Rosary, read a Gospel passage, or bring one person or one worry and stay with it. At Benediction you may hear two Latin hymns; the bishops name the Tantum Ergo among the prayers used. A guest who is not Catholic is welcome to take a seat and share the quiet, with no gesture required.
Good to know before you go: pilgrims often meet adoration for the first time at a shrine. At Tyburn Convent in London the nuns keep it day and night and the church is open from 6:30 a.m. to 8:30 p.m. At the Catholic shrine in Walsingham it is held in the Chapel of Reconciliation from 10:30 to 11:30 a.m. Monday to Saturday and from 2:00 to 3:30 p.m. daily. In Cologne Cathedral the Sacrament Chapel is reserved for prayer and adoration and is free to enter. These times were checked on October 10, 2026; shrines change their programs by season, so look at the day's schedule when you arrive.