I've been noticing on subway route maps in the subway stations a Ming Tombs station.

If you get off on the Chanping Subway Line at Tomb Station, come out of the subway station and there's an opening in the concrete wall you go through. Just follow the local people. Be careful, a bunch of hungry taxi drivers are there. Walk down and around the corner you'll come out in the town. Cross the busy street and find the bus stop with #67. Get on that bus and make sure you're going north. You will see the big entrance of the tombs as you go north. That's when you want to get off of the bus.