When faced with such inexplicable splendor, any Christian must stop and ask, “What is this about? Why did someone take such trouble, go to such expense and make such sacrifices to create a temple such as this?”
The simple Protestant may well protest and say, “But this is money that could be spent on the poor. Jesus was a simple carpenter. How does this honor him? Surely the simple worship of one born in a manger should be simple and bare?”
While all this is true, it is also true that Jesus Christ is the Lord of Glory. He reigns now on high above all the cherubim and seraphim as the Master of the Universe, our Cosmic King. The Book of Revelation pulls back the curtain and shows us the worship of heaven, where all fall down before the Lamb, where there is no need of sun or moon for the Lamb himself is the Light.
A church like this takes us there to the very threshold of heaven.
But the beauty of Catholicism is that not every church is so grand. The Mass also takes place in the most humble of circumstances–in a barren chapel in drought stricken Africa, amongst the poorest of the poor in a convent of the Missionaries of Charity, in a prison, in a barn among refugees, in a cell in Auschwitz, and when the Mass is celebrated in these dark places they become as splendid as this glorious temple—if we but had eyes to see.
UPDATE: The church is the Cathedral of St. Vladimir, in Kiev. hat tip to the Roving Medievalist.