1887 - 1929

1887: The swimming pool, engine room and bakery constructed. The Higher Line library transferred to the Third Line building. The old Higher Line library became Rhetoric classrooms. The new study hall and refectory completed. The Higher Line cricket ground levelled off.

1888: A Post Office set up in the avenue lodge. This continued to exist until 1970

1895: The Cross erected in the cemetery commemorating those whose remains were transferred from Mainham in 1866.

1902: The old gymnasium erected. It had been a temporary church in Letterkenny while the cathedral there was under construction.

1907: The new Boys' Chapel begun. It cost £14,000. The Red House was built as an isolation hospital at a cost of £765.

1912: The Higher Line cricket pavilion built.

1914: Centenary celebrations. An organ built and erected in the boys' chapel at a cost of £800. The Easter vacation introduced.

1926: Clongowes won their first Leinster Schools' Senior Cup beating Belvedere in the final.

1929: Electric light installed in the castle and school.