Anuradhapura

A UNESCO World Heritage Site, Anuradhapura is the very first kingdom of Sri Lanka with sacred Buddhist shrines, temples, palaces, reservoirs and possibly the oldest documented tree in existence planted in 245 BCE believed to be from a branch from the tree which under which the Gautama Buddha attained enlightenment. The city preserved well into the present day stood strong for 14 centuries (437 BC–1017 AD).
Visit Ranmasu Uyana which holds within it the Sakwala Chakraya – a Stargate. The symbols carved on the rock are said to be a code that opens a stargate and allows travel from this world to others in the universe. The stargate of Anuradhapura has been noted to have nearly identical shapes and symbols to those found at Abu Ghurab in Egyptand La Puerta de Hayu Marka in Peru.

https://www.bbc.com/travel/article/20210502-the-unsolved-mystery-of-sri-lankas-stargate

Polonnaruwa

The kingdom that ruled the country from 1070 to 1232 AD, and expanded into eastern Asia during the reign of King Parakramabahu the Great. Witness ancient Sri Lankan sculpting and rock carvings across this city including Gal Vihara which showcases world-renowned statues of the Buddha: a large seated figure, another smaller seated figure, a standing figure, and a reclining figure. The kingdom known for its focus on irrigation reservoirs build by a king that ordered his people to not waste any drop of rain before it makes its way to the sea.
Take a step into a noteworthy collective of temples and dagobas from ancient times like Lankathilake Vihara, King Parakramabahu’s awe-inspiring palace, and everything in between.

Sigiriya

The 5th-century monolithic rock citadel and UNESCO World Heritage Site built during the time of King Kasyapa. This magnificent fortress embodies one of the best-preserved examples of ancient Sri Lankan urban planning and irrigation hidden amidst a tropical forest. Its rock carvings specially the gigantic section of what remains of the ‘Lion Paws’ and beautiful rock painting frescos preserved from the elements for over a millennium in a cave have become some of the most iconic showcases of national artistic heritage in Sri Lanka. The Rock Palace at the summit is a miniature city of its own and today the landscaped gardens of Sigiriya are the oldest surviving in Asia and among the oldest in the world.

Aukana

The Avukana statue, which has a height of more than 46 feet (14 m), was carved out of a large granite rock face during the 5th century, during the reign of Anuradhapura’s king Dhatusena who’s son went on to build Sigiriya. This massive Buddha statue carved out of a large single rock elaborately, towering 46ft heigh, being a specimen of excellent ancient advanced sculpture technology of the nation. It is believed to have been a competition with royal blessing between a master sculptor and his student in which the teacher came out victorious. This claim is supported by an incomplete statue in close proximity which is equally mesmering. Aukana meaning ‘sun eating’ or dawn, the statue’s finely carved features are best viewed early in the morning.