Closing costs cover the legal, administrative and tax work of transferring ownership: notary or escrow fees, title search and title insurance, loan-origination charges, appraisal, recording fees, transfer taxes and pre-paid items like property tax and home insurance.
In Switzerland, notary and land-registry fees plus property-transfer tax can reach 3–5% depending on canton (Geneva is high, Zurich much lower). In the US, buyer closing costs average 2–3%, seller closing costs 6–10% (including the agent commission).
On a CHF 800,000 Geneva purchase, notary, land registry and transfer tax can total roughly CHF 35,000 (about 4.4%), payable in cash at closing on top of the down payment.