Since 1912, it is the seat of the municipality of Santa Catarina, which comprises the central western part and much of the interior of the island.

Assomada lies at about 550 m (1,800 ft) elevation on a plateau surrounded by mountains, farmland, and hills in the center of Santa Catarina.

Assomada lies near the midpoint of the highway that runs the length of the island of Santiago from Praia (the capital) in the south to the northern port of Tarrafal (EN1-ST01).

Assomada is subdivided into 22 neighborhoods including Achada Riba, Atrás de Banco, Bolanha, the City Center (central part), Chã de Santos, Covão, Covão Ribeiro, Cruz Vermelha, Cumbém (located in the south), Cutelo, Cutelo Somada, Espinho Branco, Leiria, Lém Vieira, Matinho, Nhagar (located in the north), Pedra Barro, Ponta Fonte Lima, Portãozinho, Tarafalinho and Tras da Empa (Traz d'Empa).

The "summit city" as it is kindly called by its locals and the outsiders is increasingly consolidating its economic success and self-sustainability.