Once you come back down be sure to visit the rest of the church, most of which dates to the 16th century and features some beautiful stained glass. There's also a cafe serving tasty and reasonably priced food and coffee. There's something soothing about sipping a mocha under medieval arches. If the weather is good, you can sit in the garden and enjoy views of the Radcliffe Camera and All Souls College.

An even more interesting and much easier climb is up the Old Saxon Tower of St. Michael at the North Gate. While it's not as high as the spire of St. Mary's, it's the oldest building in Oxford. It dates to the late Saxon times and was built around 1040. This used to guard the city gate of Oxford, but all that's left is the tower. Climbing up here you'll see a little museum filled with medieval and renaissance bric-a-brac, including a raunchy church sculpture I'll blog about later. On one landing is an old clockwork mechanism. If you put 20 pence in it, the gears grind to life and chimes start to play. The last time I climbed this tower with a kid I spent a whole pound on it!

Peering over the parapet you can watch shoppers stroll along Cornmarket St., Oxford's busiest pedestrian road, and you can see birds wheel and soar amidst the spires of nearby colleges. The 13th century church downstairs is worth a look for its rare medieval stained glass and a font that William Shakespeare stood next to as his godchild was baptized. It was the kid of a local innkeeper, and I hope The Bard got a few free pints for his trouble!

If you know anyone who works at or graduated from Oxford, try to get into their college and climb up one of the towers. While most colleges are open to visitors for at least part of the year, the "dreaming spires" generally aren't, so you need an insider to gain access.