Write SQL query to solve given problem: Which residential area in Arecibo county has the highest average house value? Please give its zip_code.. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T1.zip_code FROM zip_data AS T1 INNER JOIN country AS T2 ON T1.zip_code = T2.zip_code WHERE T2.county = 'ARECIBO' ORDER BY T1.avg_house_value DESC LIMIT 1