Government offices do this for tax purposes. Real estate appraisers look into the quality and condition of the property. They also look at its design. They gather information by taking measurements and speaking with people who know the history of the property. They also search public records of sales, leases, and assessments.
Appraisers compare the property with data that they have on similar properties.
They use this to make an estimate. They may also estimate the how much it would cost to re-build. Appraisers may estimate how much the value of the property has declined over time. They must think about many things that could influence the present and future value of the property. These include the location of the properties, potential income, current market conditions, and real estate trends.