What gves you a feeling of grandeur ? What gives you goosebumps ?
My personal number 1: Siegfried's funeral march from Wagner, the King Kong of epic music. You will have to hear it twice and even though the sound quality isn't that good, turn the volume up !
I usually don't like operas. I don't like the singing, but I love a couple of the pure instrumental parts and Wagner's Ring operas are so full of mind-blowing stuff that these are an exception. This is the most epic piece of music I have ever heard ! The famous Valkyries's Ride and the Rheingold prelude are nearly as epic, but I'm going to mention just one piece per composer here.
Number 2: The final of Les Preludes fom Liszt (skip to 8:45 of part two if you are impatient)
Number 3: Lacrimosa from Mozart's Requiem
Mozart is the ultimate master of doing things perfectly right at the very first try... and this piece of music is perfect, period!