Archdale King on the Lenten Statio and Tituli
"The term 'station', which we find in our Roman missals, is a reminder that Rome is the centre of Christendom, and we are referred back to a liturgy over twelve centuries old, when the Pope, surrounded by his clergy and people, celebrated a solemn Mass in the basilicas and parish churches (tituli) of the city.
Titulus or 'title', the name given to the original twenty-five parish churches of Rome, seems to have been suggested by a passage in the book of Genesis, which is found today in the rite for the consecration of an altar: 'And Jacob said: How terrible is this place; this is no other but the house of God and the gate of heaven. And Jacob arising in the morning took the stone which he had laid under his head, and set it up for a title (erexit in titulum), pouring oil upon the top of it.
Thus, in early Christian usage, a 'title' signified a consecrated altar of stone, and in a wider sense the church that contained the altar... these twenty-five tituli or parish churches were certainly in existence in the 5th-century, and the priest attached to them received the name of 'cardinals' (incardinati). A relic of this practice is found today in a cardinal receiving one of these ancient churches by way of a 'title'.
'Station' is a military term, which, in the ecclesiastical terminology of the 2nd-century, implied a day on which Christians 'mounted guard', choosing for this purpose the actual hours at which the imperial legionaries were accustomed to change guard.
'Christians', declared Tertullian, 'are the militia of God'; while St Ambrose said in a sermon that 'our fasts are our encampments against the attacks of the evil one; and we call them 'stationes' because we assist on our feet (stantes).'
The 'stations' were originally semi-fast days... later the term 'station' came to imply a liturgical reunion, and it was used in this sense in North Africa from the middle of the 3rd century, and in Rome a century later...
'Statio' came finally to denote a solemn liturgy celebrated by the Pope or his delegate, either in one of the basilicas or, with the growing cult of the martyrs, in a cemetery... The stational Mass was concelebrated, and on Sundays, when the parish priests were required in their own tituli, the Pope, as a symbol of unity and communion, sent them a particle from his Mass known as the fermentum.
It is not known who it was that perfected the system of stations, as we find them in the 7th and 8th centuries, but they were probably arranged in three successive stages, following the phases of the Lenten fast...
The stational liturgy began normally at about the hour of none, that is 3p.m. The Pope, with his clergy and faithful, assembled in the basilica which had been appointed as the assembly place (collecta). A prayer, called the 'oratio ad collectam' or 'collecta', was then said, and a procession was made to the church at which the stational Mass was to be celebrated. Preceded by the cross, the whole assembly sang psalms, antiphons and the litany of the saints, when the name 'litany' was given to the procession. "
Those of us who watched the Liturgy of Ash Wednesday in Rome would have seen the above being done, as the Pope gathered with the clergy and people at San Anselmo and then went in procession, singing the litany, to Santa Sabina (photo above).