noun, noun-modifying (irregular)
old building; old construction
Used primarily in real estate to describe older properties, often with a nuance of being dated or less desirable. Can function as a noun or prenominally.
This property is an old building, but it has been renovated.
築古マンションは家賃が安い傾向がある。
Older apartments tend to have lower rent.
Compound of 築 (ちく, 'construction') and 古 (ふる, 'old'). The reading ふる for 古 is a common native Japanese reading used in compounds.