The Eiffel Tower, one of the world's prime tourist attractions, was closed Wednesday after staff went on strike, the tower's operator said.
The strike on the 100th anniversary of the death of engineer Gustave Eiffel, who built the tower, was to protest about "the current way it is managed", the hard-left CGT union said in a statement.
The tower's operator SETE was "headed for disaster", it said.
The CGT said management was running the Eiffel Tower according to a business model that was "too ambitious and unsustainable" and that it said was based on an inflated estimate of future visitor numbers, while under-estimating construction costs.
SETE apologised to visitors, advising anyone with electronic tickets for Wednesday "to check their email" for more information on their booking.
The Eiffel Tower -- Paris's most famous landmark -- attracts nearly seven million visitors a year, around three-quarters of them foreigners, according to its website.
During the Covid pandemic numbers dropped sharply due to closures and travel restrictions, but recovered to 5.9 million in 2022.
The CGT said the tower's management was basing its future budget on 7.4 million annual visitors, although "this level has never been reached".
Eiffel died on December 27, 1923, at the age of 91.