Here's the entire text of the cornerstone:
To God in Unity and Trinity.
The sacred, auspicious stone of
this metropolitan temple,
bidden to bear the name of St. Paul,
was duly laid on the second day of June, A.D. 1907.
To restore all things in Christ.
The last line of this inscription comes from the title of Pius X's 1903 encyclical, which was his first:
You can read an English translation by clicking on the title above. It's sort of convoluted and fancily phrased, as befits the time and the occasion. However, the salient points, summarized as follows, still apply today, and perhaps even more so:
1. Times are tough.
2. The only way through is Jesus Christ.
3. He is found through the Church.
4. The Church needs (more) holy priests.
5. All things will be restored in Christ primarily through the laity's charitable works, religious associations and deeper religious instruction.
And certainly in line with the needs of the Church and her agenda today.
We would probably state it a little bit differently for our own time,
but the basics remain remarkably similar.