Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Location | Building | Year | km | Monument |
| --- | --- | --- | --- | --- |
| Bischofsheim | Station building | 1958 | 08.25 | * |
| Rüsselsheim | Linesmen house | 1863 | 12.80 | * |
| Raunheim | Station building | 1863 | 15.87 | * |
| Raunheim | Linesmen house | 1863 | 17.39 | * |
| Kelsterbach | Rail bridge | 1863 | 21.75 |  |
| Kelsterbach | Linesmen house | 1863 | 23.60 | * |
| Kelsterbach | Station building | 1863 | 23.81 | * |
| Stadion | Station building | 1879 | 31.37 | * |
| Niederrad | Station building | 1882 | 33.19 | * |
| Sachsenhausen | Rail bridge | 1864 | 34.47 |  |
Question:
what is the total number of buildings that are monuments?
Answer:
8