It is an impressive building of neoclassical architecture and a rectangular "U" ground-plan shape. It is three-story high and consists of the basement (auxiliary spaces), the ground-floor (classrooms) and the first floor (library and ceremonial room). The facade is covered by white marble.

It was built between 1888 and 1890 by Argyris Adalis, a local architect, who had also worked as assistant to the German architects, Hansen and Ziller. Its construction was financed by the island’s benefactors, M.Mitrelias and Z.Vournazos. In 1912 it was used by the Greek liberating army.

Today, the building houses the First High-School of Mytilene and attracts many visitors. It is located in the center of the city and is a touchstone for the local society.