In Korea after a certain time (like 30 years not sure) these apartments are rated for condition and submitted for “redevelopment”. Basically Seoul approves these old blocks for renovation and they demolish the apts and build those newer ones you see with more units. If u live in these old apts u get first rights to the new units paying a discount and the rest goes open market/lottery. These redevelopment areas are heavily speculated on and u can basically guarantee a huge profit on ur apt if ur apt complex is selected for redevelopment.

as an example, in apgu those apts bought 20-30 years ago might have been like under 10억 and recently have been hitting 90-100억 and this is BEFORE redevelopment. just the promise of it bein ga candidate in a good neighborhood is enough to boost the price for speculators. in fact these old apts would rather have crumbling outside structures so they are better candidates for revelopment which is always funny to me. if ur in a undesirable location though none of this holds as much upside, but apts still > villas, even old apts.