In September 1949, 19 pupils began their first day in a single classroom at Ninian Park Boys' School.
While the rest of the building was used for English-language lessons, this was Cardiff's first Welsh-medium school.
Seventy years later, the city has 17 primary schools teaching in the language and three secondary schools, with plans for a fourth.
A parade on Saturday marked the anniversary as part of the annual Tafwyl festival.
"The aim is to celebrate the incredible growth there has been in Cardiff's Welsh-medium schools since we both were among a handful of the earliest pupils," said Iolo Walters, who helped plan the event with Alwyn Evans.
"By now, our grandchildren are the third generation to attend these Welsh-medium schools."
They have produced many notable personalities - including actors Matthew Rhys and Ioan Gruffydd and rugby stars Jamie Roberts and Rhys Patchell.
When the first school was opened, only pupils from Welsh-speaking homes were accepted.
One of the original 19 children, John Ellerman, was transferred to Kitchener Road School because his parents did not speak Welsh.
While the rest of the building was used for English-language lessons, this was Cardiff's first Welsh-medium school.
Seventy years later, the city has 17 primary schools teaching in the language and three secondary schools, with plans for a fourth.
A parade on Saturday marked the anniversary as part of the annual Tafwyl festival.
"The aim is to celebrate the incredible growth there has been in Cardiff's Welsh-medium schools since we both were among a handful of the earliest pupils," said Iolo Walters, who helped plan the event with Alwyn Evans.
"By now, our grandchildren are the third generation to attend these Welsh-medium schools."
They have produced many notable personalities - including actors Matthew Rhys and Ioan Gruffydd and rugby stars Jamie Roberts and Rhys Patchell.
When the first school was opened, only pupils from Welsh-speaking homes were accepted.
One of the original 19 children, John Ellerman, was transferred to Kitchener Road School because his parents did not speak Welsh.