In California, the royal road is called "El Camino Real".
The ice cream shop is right around the corner, on the royal road.
The royal road is temporarily closed for repairs, ma'am.
"the royal couple's much heralded world tour"
The King had a royal ministre in the castle
This song was recorded at Abbey Road.
dpends what you want to say about a road in your sentence.
The royal family had a feast to celebrate the king's birthday.
The wily coyote was thwarted again by the road runner.
She rode her bicycle on the road.
the king and queen lived in a Royal way. or The king wear royal robes.
You would use "at" when refering to a place or a time, for example... "I will meet you at ten o'clock." Or... "I will meet you at the corner of the road."
That parking spot was half a mile down the road, or thereabouts.
In the sentence "One day a royal messenger announced that there would be a grand ball at the Royal Palace," the article "a" is used before "royal messenger" and "grand ball" to indicate that these nouns are non-specific or general. The definite article "the" is used before "Royal Palace," signifying a specific place that is well-known. The sentence correctly employs articles to clarify the nouns and convey the intended meaning.
The courtier to the king was looking as royal as him. This is a sentence containing courtier in it.