Before continuing your exploration of Ciudad Colonial, take a quick and worthwhile detour. At the right of Alcázar de Colón is a terraced walkway leading down to the Ozama River. You will exit at this impressive gate. When Puerta de San Diego was constructed in 1576, it was the main entrance into the city from the port. Hence its alternative name Gate of the Sea. Among the heraldic symbols is the double-headed eagle of Charles I of Spain, also named Emperor Charles V (center). On the right are the Pillars of Hercules and the coat of arms of Santo Domingo.