According to Catholic Answers:

The Holy Trinity:

1. Nativity
2. Circuмcision
3. Epiphany
4. Monday within the Octave of the Resurrection
5. Tuesday within the Octave of the Resurrection
6. Ascension
7. Monday within the Octave of Pentecost
8. Tuesday within the Octave of Pentecost
9. Most Holy Trinity
10. Most Holy Body of Christ
11. Finding of the Holy Cross

The Blessed Virgin:

12. Purification BVM
13. Annunciation BVM
14. Assumption BVM
15. Nativity BVM
16. Immaculate Conception BVM (by Clement XI)

The Saints:

17. Dedication of St. Michael
18. Nativity of St. John Baptist
19. Ss. Peter and Paul
20. St. Andrew
21. St. James
22. St. John (the December feast)
23. St. Thomas
24. Ss. Philip and James
25. St. Bartholmew
26. St. Matthew
27. Ss. Simon and Jude
28. St. Matthias
29. St. Stephen (the December feast)
30. The Holy Innocents
31. St. Lawrence
32. St. Sylvester
33. St. Joseph
34. St. Anne
35. All Saints
36. Principle Patrons of Country, City, etc.

It is my understanding that these holy days were on the universal calendar but by the 1900s few countries, if any, celebrated most of these as holy days.  According to Catholic Encyclopedia, Pope St. Pius X reduced the number of holy days of obligation to those that were more typically celebrated worldwide in order to make the list of holy days for the universal church to be more uniform throughout the world.

Prior to this change by Pope St. Pius X, most of these feasts were not, for example, obligatory in the United States.