The town of Tawau is located in eastern Borneo , near the Indonesian border. This rather gloomy town reflects a painful past, such as the conflict between colonizing countries, its utter destruction during World War Two and even bombardments during the subsequent tension between Indonesia and Malaysia.
Today, even though this greyish town is the third largest in Sabah state, not only do I find it devoid of interest, but it seems to not want to render itself attractive. Only the religious side of things is potentially interesting: there are a few mosques scattered around town including the imposing Al-Kauthar, Borneo's biggest mosque. You also also find a Hindu or a Buddhist temple, as well as a charming church (Holy Trinity) built by Catholic Indonesians.
Unless you are catching an evening flight or you want to meet people who live here, I suggest you do not tarry here, but rather direct your stay in Malaysia towards Borneo's real assets.