Some of Oxford's museum's saw visitor figures plummet in 2020.
New research shows UK tourism sites as a whole saw a 70% drop, compared to 2019.
The worst affected venues were London's Royal Museums Greenwich and Edinburgh Castle.
Locally, the Oxford University Museum of Natural History saw a 79% fall, whilst the Ashmolean Museum faced a 74% reduction in visitors last year.
The Pitt Rivers Museum, Blenheim Palace and Oxford's Botanical Gardens suffered drops of 76%, 58% and 42% respectively.
The Association of Leading Visitor Attractions - which represents venues including museums, zoos and theme parks - wants them to reopen at the same time as retail next month.
Under Boris Johnson’s road map for easing coronavirus lockdown restrictions, the earliest non-essential retailers can reopen is April 12.
Although that is the same date for outdoor attractions such as zoos and theme parks, indoor venues including museums and galleries must wait until May 17.
The Easter and May Day bank holidays are normally crucial for the tourism sector.
Bernard Donoghue, Director at ALVA, told the PA news agency: 'There is huge disappointment that indoor visitor attractions in England can’t open until the 17th of May, five weeks after non-essential retail.
'That’s something that we just don’t understand and have been raising with Government.
'It’s extraordinary to me that you can open Primark and H&M but not the Tate and V&A (Victoria and Albert Museum).
'Not least because, according to Public Health England, there hasn’t been a single case of coronavirus transmission at a visitor attraction in the UK. They’ve proved to be Covid safe.'
Some 45.4 million visits were recorded across 294 sites in the UK last year, down from 151.3 million during 2019.
The government says the roadmap out of lockdown will be done in a "cautious, phased way."
A spokesperson added: 'Our support for the arts is unprecedented, with a package worth nearly £2 billion helping save over 75,000 jobs. We are doing all we can to help our world-class attractions return strongly and open as soon as possible.'