We made a stop over at Perak Tong from Penang to Cameron Highlands.
You need not to be a devotee to admire the incredible graffiti on the granite wall.
Perak Tong (Perak Cave) is about 5 minutes drive from the Plus Highway exit towards Sungai Siput (on Jalan Kuala Kangsar).
The snapshots were taken handheld in the dim caves. I think I should visit with proper gears and spend more time in the future to make a record of the awesome drawings and calligraphy.