The visitors of Ioulis have the opportunity to admire two significant architectural monuments, both works of the great German architect Ernst Ziller, the new Town Hall and the historic Town Hall of the island.
The historic Town Hall is a remarkable neoclassical building of 1902, decorated by finds from the archeological sites of the island. In its façade stand out the clay statues of Hermes and Apollo, while on the western side an ancient female sculpture and a relief of the classical era have been built into the wall. Inside the building more reliefs have been built into the walls while the conference room of the Municipal Council contains impressive ceiling paintings.