Anuradhapura
You should go to Anuradhapura, presenting yourself not as a simple tourist, but as a pilgrim.
Then you can experience delight by sitting on the ground under the sacred Bo, the oldest tree on earth (a seedling brought from India 23 centuries ago, and still grows, but the Bodha tree itself has not survived ), or by touching the footprint of the Buddha, which he left while walking around the island.
Stand on Jetavan ("the place where the rays of liberation shone") - here the monk Mahinda read sermons - and touch the stone with a piece of sash walled up inside, which the Buddha girded with.