Fewer schools are taking pupils on educational trips to Wales's historic sites, new statistics show.
Figures obtained by the Tories show a 21 per cent drop in visits by pupils to locations maintained by Cadw, the Welsh heritage body, over the past decade.
In 2008-09, schools took 86,956 trips, compared with 110,096 in 1999-2000.
Cadw offers free educational visits to its sites, including Roman ruins, medieval castles and former industrial sites.
Paul Davies, shadow education minister said health and safety rules and financial constraints could be putting schools off visits.
"Children deserve the broadest possible educational experience," he said. "They must not be disadvantaged by red tape and lack of money."
Cadw said feedback from schools suggested the main reason for the dip was transport costs.
An Assembly government spokeswoman said visits offer an "opportunity to enrich young people's learning, raise their self-esteem, increase their motivation and appetite for learning and raise levels of achievement."
Last week, the Assembly government launched detailed guidelines for school trips with the aim of moving away from a "cotton-wool culture" and exposing pupils to more risk.
The document was widely welcomed, but there were warnings that some guidelines could be expensive and time-consuming for smaller schools. de.