Passage: The Buland Darwaza is made of red and buff sandstone, decorated by white and black marble and is higher than the courtyard of the mosque. The Buland Darwaza is symmetrical and is topped by large free standing kiosks, which are the chhatris. It also has terrace edge gallery-kiosks on the roof, stylized buckler-battlements, small minar-spires, and inlay work with white and black marble. On the outside a long flight of steps sweeps down the hill giving the gateway additional height. It is 40 metres high and 50 metres from the ground. The total height of the structure is about 54 metres from the ground level. It is a 15-storied high gateway acting as the southern entrance of the city of Fatehpur Sikri. The approach to the gate consists of 42 steps.

Question: How many meters high is the terrace?
40