The Manila City Hall during 1901 was made up of Oregon pine which covered one-third of the area used by the current building. After 31 years of occupancy, City Engineer Santiago Artiaga suggested reinforcing the floor of the weakened structure supporting the session hall used by the municipal board and avoid the accommodation of too many people along the corridors and in the hallway.
The building sits on a trapezoidal shape of the lot in between the Legislative and Post Office buildings. Due to the monotony of the building envelope, one cannot distinguish the principal facade from the main entrance properly. The south entrance has a balcony emphasized by three arches resting on Corinthian columns while the north entrance has the same design treatment but has pediments and a tall, hexagonal clock tower capped by a dome.
The clock tower, also designed by Antonio Toledo which was completed during the 1930s is the largest clock tower in the Philippines. It stands out during nighttime when the whole of the tower lights up. Every hour, they rung the bell three times continued by a melody. It has now become the icon for the city of Manila.
Source - https://en.wikipedia.org/wiki/Manila_City_Hall
The City Hall is the main administrative building and houses the local government of the city of Manila.
The long and large building that houses the office of Mayor was built in 1941.