Which are among Oman's most famous forts stand at the entrance to Muscat bay. Mirani, which was built before the arrival of the Portuguese, was originally shaped like a tower. Then in 1588 the Portuguese rebuilt it on the ruins of its old structure, adding emplacements, stores, living quarters for the commander and a place of worship. The building was enlarged to its present size in the reign of Imam Ahmed bin Said, the founder of the Al Busaidi state in the 18th century, and his grandson Sayyid Said bin Sultan, at the beginning of the 19th century.