Register Officer Janet Taubman said many more couples than expected were asking about civil "weddings" and the first dates had already been provisionally booked.
The Register Office and The Walker gallery have spent £3,500 restoring two Old Masters to hang on the walls.
Called Meadow Sweet and River Road, the large paintings will be less likely to offend people and are "more suitable".
Mrs Taubman said: "We had two pictures up before. In one room there is a picture of a signing of the register with a young bride.
"The other was of a Romeo and Juliet on a swing.
"They were innocent pictures, but the new paintings are less likely to offend."