The architecture of Manila is not as consistent as you would see in, say, California, where a general plan is in place, giving the state a distinct Mediterranean style. Manila is in its present inconsistent state due to corruption, political instability, economic mismanagement, dictatorship and the remnants of the former dictator still intact and as influential as ever.
During the liberation of Manila in the second world war, most of the city was carpet-bombed. The Pearl of the Orient, as Manila was known before the end of the second world war, had ancient medieval cathedrals, churches, Spanish and American government buildings, stately mansions, forts, classic bridges, old-style Filipino homes with capiz windows, train stations, the Metropolitan Theatre, the Skyroom Jai Alai Building, etc.
Unfortunately, the city was never rebuilt nor recovered after the second world war, due to neglect and, of course, corruption. Today, the Luneta Hotel is abandoned, the Escolta blighted, the Pasig River polluted, Intramuros remains in ruins, street names constantly change, and modern boxed buildings slowly obliterate the classic Manila. Burnham's City Beautiful Plan remains an elusive dream. The calesas (horse-drawn carriages) are all but gone.
There are still a few calesas on the streets of Manila, but they are expensive compared to taxis and tricycles. Try visiting the Chinese cemetery in the centre. I agree with other points in this post.
Is this your business?