The first and closest option would be to visit the Dambulla cave temple. You're likely to have seen numerous pictures of this iconic spot, which holds a lot of religious and cultural value. The complex is full of caves, which will take you a couple of hours to explore and take in. The caves brim with Buddha statues, over 150 of them. The walls of the caves are also filled with murals and colourful paintings that are centuries old, which makes it feel as if you've stepped into a bygone era. This is also a great way to teach the history of Sri Lanka and Buddhism to young kids!