Beata Es, Virgo Maria is the Offertory for today's Feast of the Visitation. Here's a video of this beautifully melismatic chant:
Here's the full chant score:
The words in English are: "Blessed art thou, O Virgin Mary, who didst bear the Creator of all things: thou didst bring forth Him Who made thee, and remainest forever a virgin. Alleluia."
Here is an mp3 of Beata Es, Virgo Maria from the Brazilian Benedictines, and here are all the mass chants and chant scores for this feast from their site.
I don't have the list of office hymns that are sung specifically on this day - but the LLPB appoints this hymn, "The God Whom Earth and Sea and Sky" (that's the mp3) (Quem terra, pontus, aethera) to "The Common of Saints - A hymn about the Blessed Virgin Mary." This one is, in fact, very fitting for The Visitation. And of course, the Visitation itself (from Luke 1:39-56) is the source of the Magnificat, the canticle sung every day at Vespers.
Here's the TPL page for this hymn, where it says:
This hymn was composed by Venantius Fortunatus (530-609), Bishop of Poitiers, and has been an important part of devotions to the Blessed Virgin Mary since the early Middle Ages. Today it is used in the Little Office of the Blessed Virgin Mary daily as a hymn for the Office of the Readings and also as the hymn for Friday Lauds. In the Liturgy of the Hours it is found in the Common of the Blessed Virgin Mary as the hymn for the Office of the Readings.
Ah, Fortunatus - my favorite! TPL, in fact, has an entire section devoted to the Blessed Virgin Mary.
Here is Textweek's page of art images for this feast; here's one from 1306, by Giotto di Bondone:
Here's the description of this fresco at Web Gallery of Art:
The pregnant Mother of God and her two companions visit Elizabeth, who is expecting John the Baptist. The two women embrace in front of the portico. As so often, Giotto places the intensity of the encounter in the exchange of glances. Beneath this fresco the wall, decorated with painted marble, appears to open up: Giotto here shows us a view of a chapel with cross-rib vaulting and a narrow Gothic window. A chandelier hangs from the vertex of the vault defining the depth of this unusual, illusionistically painted space.
The figure in the right was strongly damaged by the humidity.
From "Speaking to the Soul," at Episcopal Cafe:
At first I had no idea where the lovely Magnificat we sang every night was from: “My soul magnifies the Lord, my spirit rejoices in God my savior” (Luke 1:46). When I eventually found it in the first chapter of Luke’s Gospel, I was startled but glad to see that it was one pregnant woman’s response to a blessing from another. It is the song Mary sings after she has walked to her cousin Elizabeth’s village, and on greeting Mary, Elizabeth, who is bearing John the Baptist, recognizes that Mary bears the Messiah. . . .
The Magnificat’s message is so subversive that for a period during the 1980s the government of Guatemala banned its public recitation (a sanction that I’m sure the monasteries in that country violated daily). But when I came to its words knowing so little about them, I found that all too often they were words I could sing with ease at evening prayer, with a facile (and sometimes sleepy) acceptance. On other nights, however, they were a mother’s words, probing uncomfortably into my life. How rich had I been that day, how full of myself? Too full to recognize need and hunger, my own or anyone else’s? So powerfully providing for myself that I couldn’t admit my need for the help of others? Too busy to know a blessing when it came to me?
From “Virgin Mary, Mother of God” in Amazing Grace: A Vocabulary of Faith by Kathleen Norris (Riverhead Books, 1998).