This is a non-current or long term asset which represents the total cost of the building or buildings you own. This total cost will be depreciated over time depending on its useful life. You don't include land value here at all, that asset should be separated.
What's included
The purchase price of the building
Costs directly attributable to getting it to the location and condition necessary for the building to be rented out or used properly
Any borrowing costs capitalised
What's not included
The value of the land that the building sits on is not included in the cost of buildings
Accumulated Depreciation - Should be recorded against a separate liability account and represents the total reduction in value of the building over its useful life