The subway, the train, the T, the underground, the metro, the tube-whatever you call it, it's how we get around. Boston's happens to be the first, and when one has the world's most ancient subway system, it's easy to dismiss it as old news. But the MBTA has a big birthday this year, and it deserves its rightful centennial celebration. FM's editors took our Saturdays and Sundays and made our way to the far reaches of the lines. Some of us went for a walk. One of us went home. For some, inspiration struck in liquids of varying kinds. Oil and water, you could say. Or ink and gin. For others, it turns out the T is a deeply personal affair, even if it's one that's easily eavesdropped upon. Moral of the story? Go somewhere. If the T stops, don't groan. Find the end of the line. When you're reentering HarvardSquare, if you're going outbound, look out your right window; find the gnome, the abandoned station it marks, For the week, we played "I Spy." This is what we saw.