Riddle 91

“A bird in the hand is worth two in the bush,”
How often we ’ve heard those old words,
And my total, I have it on evidence strong,
Is exactly the worth of two birds.

The dome of St. Paul’s is my first, my last;
The dome of St. Peter’s is, too;
But if you should go there and see for yourself,
You would say that this is n’t true.