i. Along the path which begins in the area of Saint Spyridon and which ends in the gulf of Otzia, you will meet the famous Leonta or Lionta (lion) which is the landmark of the island. This is an archaic carving of a lion on a rock of the 7th-6th BC, the length of about 8 meters.
ii. There are two lighthouses on the island. One is the lighthouse of Saint Nicolaos and can be found at the entrance of the island’s port. It is built on the ruins of the temple of Poseidon. It was built in 1831, has a height of 8 meters and was the first lighthouse that was lit in the Cyclades and the second in recent Greek history.
The lighthouse of Tamelos cape was built in 1983 in order to light the passage between Kea and Kythnos. The tower of the lighthouse is 7,5 meters high.
iii. Karthaia is the most significant archaeological site of the island. It consists of an acropolis fortressed with walls which are over 2 km in length with gates, towers and boulders.
The significant findings from excavations of Karthaia are exhibited in the Archaeological Museum of Ioulida.
iv. In the interior of the settlement of Korissia, a chimney which is 45 meters high will catch your eye. This chimney of the enamel factory, which was the only one to manufacture enamel plated pots and it was the biggest in the Mediterranean. This factory was in operation between 1927 and 1957 and played an important role in the economy and the social life of the island. After 1936, the factory started to export its goods to the Balkans and the Middle East and employed 300 workers.
v. Two great architectural monuments built by the German architect Ernst Tziller (1837-1923) are the New Town Hall and Historic Town Hall which was built in 1902.