Tirtanadi Water Tower is one of Medan's most recognisable colonial landmarks: a tall, iron-framed water tower built in 1908 when the Dutch colonial city was expanding around its new utilities. It still stands above the traffic near Jalan Sisingamangaraja, less as a polished museum piece than as a working fragment of the city's early modern infrastructure.
You usually see it from the street rather than tour it inside, but it is worth a short detour if you are already exploring central Medan's older buildings. The appeal is architectural and historical: the tower helps explain how Medan grew from plantation boomtown into North Sumatra's main city, and it makes a useful photo stop on the way between the Grand Mosque and the old commercial quarter.