The last things built at the north end of the complex were four white marble minarets, one on each corner of the white marble plinth of the tomb building, each 40 meters tall. Taj Minarets are tall towers, usually located next to the mosque. The Muslim crier climbs the staircase inside the tower and calls the Muslims faithful for prayers.
The Mosque needed only one minaret, but Shah Jahan erected four to keep the whole complex perfectly symmetrical. The minarets were built at the equal height of the tomb and slightly away from the plinth so that if they ever collapsed, they would fall away from the tomb without damaging it.