A hymn commonly sung to Old 100th is "Praise God, from Whom All Blessings Flow," often known simply as The Doxology, written in 1674 by Thomas Ken, a clergyman in the Church of England.
Praise God, from Whom all blessings flow;
Praise Him, all creatures here below;
Praise Him above, ye heavenly host;
Praise Father, Son, and Holy Ghost.