The aviary at ZSL London Zoo was built in 1965 and is considered to be in need of repairs
A 16th Century shipwreck and London Zoo's aviary are among English heritage sites now considered to be at risk.
Also added to Historic England's latest Heritage at Risk Register are Brighton Old Town and a church dubbed "the birthplace of feminism".
The sites are considered to be at risk of being lost through neglect or decay.
But Historic England said there are fewer entries on the register than last year.
Sites including the Grade-I listed grounds at Castle Howard in North Yorkshire and the world's oldest "pub music hall", Wilton's Music Hall in London, have come off the register after being restored and saved.
See more historic and quirky buildings on BBC England's Pinterest board, external
Experts warned that the gap between the cost of repairs and the value of restored properties was growing, driven partly by a skills shortage and a lack of scaffolding in some areas which pushed up costs.
Duncan Wilson, chief executive of the government heritage agency, said "thousands of historic sites" were at risk of being lost across the country.
"Many lie decaying and neglected and the gap between the cost of repair and their end value is growing," he said.
"The good news is this year there are fewer entries on the Heritage at Risk Register than last year.
"But as some places are rescued, others fall into disrepair."
Another site added to the list is Newington Green Unitarian Church in Stoke Newington, London, dubbed "the birthplace of feminism"
London Zoo's aviary, designed by Lord Snowdon and built in 1965, is in need of repair but has secured Heritage Lottery funding to turn it into a new space for animals and visitors.
A 16th Century shipwreck in Dunwich, Suffolk, thought to be that of an armed merchant vessel, has been added to the list after a bronze gun was stolen from the site.
