Percentage allocation is one way to make a decision. Since you don't have a breakdown on the tax assessment you can use the information below to separate the values.
If your personality is aggressive, you may want to allocate 80% of the value to the building and 20% of the value to the land. If your personality is conservative, you may want to allocate 60% of the value to the building and 40% of the land.
Separating cost of land and buildings. If you buy buildings and your cost includes the cost of the land on which they stand, you must divide the cost between the land and the buildings to figure the basis for depreciation of the buildings. The part of the cost that you allocate to each asset is the ratio of the fair market value of that asset to the fair market value of the whole property at the time you buy it.