At the time Geoffrey Chaucer wrote the General Prologue and the twenty-four stories in The Canterbury Tales, pilgrimages—journeys to sacred places undertaken as an act of religious devotion, an act of contrition for the forgiveness of sins, or to seek a miraculous cure from an illness—were a fairly common occurrence in medieval Europe. The shrines to which the pilgrims journeyed usually exhibited relics of saints or other holy persons, such as bones or personal items—some even claimed to display the nails and pieces of the cross on which Jesus Christ was crucified.
The ultimate place of pilgrimage was the Holy Land, particularly the sites associated with Jesus Christ at Bethlehem, Nazareth, and Jerusalem. The journey to the Holy Land was arduous and could be very dangerous, but there were many other sacred sites to which pilgrims travelled that didn't require such a difficult journey. Rome, Santiago de Compostela in Spain, and Notre Dame in Paris were popular pilgrimage destinations for Europeans.
Enterprising individuals organized less arduous and significantly less dangerous pilgrimages for Londoners and other religious believers in the British Isles to local shrines in England, Ireland, Scotland, and Wales, including shrines at the major cathedrals of St. Albans, St. Andrews, and St. David's.
In the General Prologue of The Canterbury Tales, the narrator, who is Geoffrey Chaucer himself, tells the reader that he's spending the night at the Tabard Inn in Southwark, a fairly lawless suburb of London located on the south bank of the Thames across from the City of London, and known in medieval times as a notorious center of "entertainment."
The narrator intends to make a pilgrimage alone to Canterbury to visit the shrine to St. Thomas Beckett at Canterbury Cathedral, where it's believed that Thomas Beckett, Archbishop of Canterbury, was murdered in 1170 by four knights at the suggestion, or possibly at the order, of King Henry II.
The Tabard Inn was a popular gathering place and stopping-off place for pilgrims on their way to Canterbury from London and other parts of England.
That evening, a group of pilgrims who are also going to Canterbury arrive at the Tabard Inn.
There came at nightfall to that hostelry
Some nine and twenty in a company
Of sundry persons who had chanced to fall
In fellowship, and pilgrims were they all
That toward Canterbury town would ride. (General Prologue, 23–27)
The narrator is apparently asked or allowed to join the group, which plans to set out for Canterbury early the next morning.
So had I spoken with them, every one,
That I was of their fellowship anon,
And made agreement that we’d early rise
To take our way, as to you I’ll devise. (General Prologue, 31–34)
"The Beckett Way," a modern reconstruction of the pilgrims' journey to Canterbury from Southwark—where only the inn yard of the Tabard Inn still remains—can be found at https://britishpilgrimage.org/portfolio/pilgrims-way-to-canterbury/