Catacombs

An archaeologist found a Mayan dungeon in a shape of a square divided into four quadrants. Each contained a network of interconnected underground pathways. The archaeologist sent four assistants to construct maps of each quadrant. After returning from the expedition, the archaeologist realized that he had failed to label the quadrants. So he put them together as shown below, but he was certain that the pathways do not form just one closed loop but many more.

Put the four maps together so that the pathways form as many closed loops as possible.

From Nobiyuki Yoshigahara's Puzzles 101