When you buy a property, the deeds are processed in the registry of deeds and then returned to the financial institution that supplies the mortgage.
Essentially, you don’t own the house until the mortgage has been paid in full so the lending institution holds on to the deeds until your mortgage has been completely paid off. So when you say, “I own a house”, in … fact you don’t. You own a mortgage. You only fully own the house when the mortgage is paid. Once you have paid off your mortgage, you can obtain the deeds. Most people just leave them with the lender as it is less hassle than trying to find a secure place to store them. Better to leave them in a secure place. Alternatively, leave them with your solicitor.