Kampung Arab could be a tourist attraction in Jakarta. It has not been developed yet so you have both the benefit of the authenticity and the disappointment of finding out the sights are not properly taken care of.
Located in Pekojan, in the Tambora district in North Jakarta, it is a 15 minutes walk from Taman Fatahillah. If you go by taxi, you can ask to be dropped at the corner of Jalan Pekojan Raya and Jalan Pengukiran Raya.
The area has several old mosques to visit, among which Masjid Al-Anshor (that I already reviewed separately as the oldest mosque in Jakarta), Langgar Tinggi and Masjid Jami' Annawier. At the time they were built, some of the worshippers were Muslim Indian merchants who helped spread Islam to the rest of Indonesia.
Langgar Tinggi
Built on stilts in 1829, Langgar Tinggi is a small mosque in the river bank of the Kali Angke. It suffers from a lack of maintenance but the atmosphere is authentic and the residents are very welcoming if you come during prayer time.
From what I could read on the internet, the architectural style of Langgar Tinggi mixes Moorish, Chinese, Javanese and colonial elements.
Masjid Jami' Annawier
The Annawier mosque is just 300 meters from Langgar Tinggi. It was built in 1760 by Sayyid Abdullah bin Hussein Alaydrus, a scholar from Hadramout (Yemen). It is one of the largest mosques in West Jakarta and it can welcome up to 1000 worshippers.
Even though Kampung Arab is not as preserved as it should, I think it is still worth visiting if you want to discover the real Jakarta.