the building is said to--one hundred years ago.1be built 2ha

把这话转化一下,去掉said咯：
1.的意思是The building was built 100 years ago.
2.的意思是The building had been built 100 years ago.
后面的时间状语是过去某个点,所以前面只要用was built 就可以了.
如果要用2 的话,改为the building is said to have been built since one hundred years ago.
所以选1
个人意见.