[iso1210]

In the UK, the land and the buildings is usually owned by some offshore company - a 'freeholder'

The right to occupy a given flat in the building is then sold for 99 or 125 years to a 'leaseholder', who also signs up to pay for the operational costs (insurance, cleaning, gardening etc) for the open area

They also agree to pay a 'ground rent', say £20-50 a month to the freeholder. That often doubles every 25 years (so about 2-3% increase per year), but sometimes doubles every 15 or even 10 years (so 7-8%)