All about Quezon

Here's a closer look at the bas-relief on the oddly-shaped Mid-Century Modern building in Quezon City Hall which I first posted more than one year ago (and before you ask, no, I still don't know what's inside the thing). I can see the Quezon Memorial and the Oblation statue of the University of the Philippines on the relief, and many of the other scenes feature Manuel L. Quezon, the first president of the Commonwealth of the Philippines and the man after whom the city is named. One particular scene strikes me the most, the one where he is ankle-deep in mud and planting rice. What I'd like to know is, until what year did the city still have rice fields??