Visited the Angono Petroglyphs last month (June 2011). The site is also referred to as the oldest known artwork in the Philippines.

The site is well-managed: nice landscaping, small but adequate museum facilities, a platform for viewing the petroglyphs.

However, transportation to the site is a little difficult. There's been no report on public transportation so independent travel to the cave area is not really that attractive. I ended up hitchhiking with locals. Other options would be to rent private vehicles.

Another issue would be the buffer zone of the site. A good part of the hill/mountain seems to be located within a private residential village.

All in all, it was a very rewarding experience.