The Lucena Position first appeared in the oldest chess text in existence, Repetition of Love and the Art of Playing Chess. This book was written in 1497, by Lucena, a Spanish priest. This is an important position to study as it often appears in King and Rook vs King Rook Pawn endgames. The idea behind Lucena Position is that Black is keeping white's King behind the pawn and preventing it from queening. If the King moves out the rook checks him back behind the pawn (white must stay beside the pawn so the black king or rook doesn't grab it). Below is the method for freeing the King from behind the pawn and getting the pawn to the back rank.
I'm pretty sure the positon below is the original position used by Lucena to describe the concepts, most important of which is building the bridge. The first move is the essential one and the reason behind it, and why it's called building a bridge, becomes clear as you go through the endgame.
+---+---+---+---+---+---+---+---+
| | | | |WK | | | | 8
+---+---+---+---+---+---+---+---+
| | | | |WP | | | | 7
+---+---+---+---+---+---+---+---+
| |BK | | | | | | | 6
+---+---+---+---+---+---+---+---+
| | | | | | | | | 5
+---+---+---+---+---+---+---+---+
| | | | | | | | | 4
+---+---+---+---+---+---+---+---+
| | | | | | | | | 3
+---+---+---+---+---+---+---+---+
| | |WR | | | | | | 2
+---+---+---+---+---+---+---+---+
| | | | | |BR | | | 1
+---+---+---+---+---+---+---+---+
A B C D E F G H
1. Rc4 Rf2
2. Kd7 Rd2+
3. Ke6 Re2+
4. Kd6 Re3
5. Rb4+ Ka7
6. Rb5 Rd3+
7. Ke6 Re3+
8. Re5 and that's that.
In Endgames where it's rook vs rook and a pawn this position is very common and one that white aims for. There is however a strategy for black to prevent this postion called Philidor's Principle. | 
