Jami-Ul-Alfar Mosque, also known as the Samman Kottu Palli, Rathu Palliya, Red Musjid, or the Red Mosque, is a notable historical Musjid in Colombo, Sri Lanka. Located on Second Cross Street in Pettah, it is one of the oldest Musjids in the city and a popular tourist attraction.

Construction of the Jami-Ul-Alfar Musjid began in 1908 and was completed by 1909. The Musjid was established by the local Indian Muslim community in Pettah to meet the needs of their five-times-daily salaah and Friday Jummah prayers. Habibu Lebbe Saibu Lebbe, an unlettered architect, designed and built the Musjid based on images and details of Indo-Saracenic structures provided by South Indian traders who commissioned him. The architectural style is a hybrid, incorporating elements from Indo-Islamic and Indian architecture, along with Gothic revival and Neo-classical styles. Initially, the Musjid could accommodate 1,500 worshippers, though only about 500 attended prayers at the time.

The Musjid is easily recognizable by its distinctive red and white candy-striped two-storey structure, complete with a clock tower. It bears a resemblance to the Jamek Mosque in Kuala Lumpur, Malaysia, which was constructed in 1910. Before other landmarks were established, the Jami-Ul-Alfar Mosque was often considered a key landmark for sailors approaching the Colombo port.

In 1975, with the help of the Haji Omar Trust, the Musjid purchased several adjoining properties and began expanding its capacity to accommodate 10,000 worshippers.