How do I get into the catacombs

Hint 1 of 14:

Have you looked in the computer Grail Diary?

Hint 2 of 14:

There is a picture of a stained glass window in there.

Hint 3 of 14:

You need to go to the room with the matching window.

Hint 4 of 14:

Now, look at the Diary again.

Hint 5 of 14:

There's something about either "to the left" or "to the right."

Hint 6 of 14:

That refers to the columns with the inscriptions.

Hint 7 of 14:

Look at the inscription on the matching column.

Hint 8 of 14:

It has Roman numerals, like the ones on the floor.

Hint 9 of 14:

The Diary also mentions something about the first, second, or third.