Kamphaeng Phet, like almost everywhere in Thailand, has a rich, UNESCO-listed cultural heritage, comprising temples and statues of Buddha erected in the 14th century.
I visited the Historical Park two kilometers from Kamphaeng Phet's center to explore the town's ancient heritage and ruins. There is a superb walk you can do there which takes you from one temple to the next and allows you to explore the ruins left behind by this now extinct civilization. There is quite a lot of vegetation there and it is all much more wild and disordered than at Ayutthaya, for example.
Once I became bored with looking at the temples, I went to Khlong Lan National Park to admire its waterfalls and dense vegetation. The park is a little haven of nature that takes the whole day to get to and explore. And beingoff the beaten track, it is not very busy.