The Grand Mosque of Medan, known as Masjid Raya Al-Mashun, was built in 1906 as the official mosque of the Sultanate of Deli — funded by the Sultan from tobacco revenues at the height of Deli's prosperity. The building's architecture blends Islamic, Moorish, Indian, and Malay elements, with five octagonal domes and a large prayer hall surrounded by wide verandas.
The mosque is open to non-Muslim visitors outside prayer times, and the staff generally welcome respectful visitors who dress modestly. It stands about 400 metres from the Maimun Palace, and the two make a natural pair. The surrounding neighbourhood contains several older colonial buildings from the Dutch period, and the general atmosphere of early-20th-century prosperity is still legible in the streetscape.