13.7700°N, 109.2111°E.
Thap Doi, also known as the Twin Towers, is a pair of Cham brick temples in the city of Quy Nhon in Binh Dinh province of central Vietnam. The temples were built in the late 12th century CE under the Cham kingdom of Vijaya, which controlled central Vietnam from its capital at nearby Cha Ban from the 11th through the 15th centuries. The two towers stand close together on a low platform; the larger reaches 20 metres in height and the smaller 18 metres. Both follow the standard Cham temple plan: a square cella with a single east-facing entrance, surmounted by a steeply tapering tower of corbelled brick courses decorated with inset pilasters, false windows, and corner garuda figures. Construction is in fired brick laid in tight joints with no visible mortar — the precise jointing technique of Cham brickwork remains imperfectly understood despite extensive analytical study. The towers were restored in the 1990s under a Polish-Vietnamese program.
Both stand intact today within the modern urban fabric of Quy Nhon.