About 100,000 people are expected at this year's Urdd Eisteddfod at the National Trust estate at Llanerchaeron in Cerdigion.
This year's event, one of the biggest youth festivals in Europe, includes a new science exhibition, GwyddonLe.
Another new attraction is "Cwtsh Cymraeg", where literary winners will be on screen reading and discussing their work.
The week-long event continues until Saturday, 5 June.
Llanerchaeron is said by the National Trust to have survived virtually unaltered as "a rare example of a self-sufficient 18th Century Welsh minor gentry estate ".
Urdd Gobaith Cymru chief executive Efa Gruffudd Jones said it was a "fabulous" site for the eisteddfod, and visitors would be able to go around the Llanerchaeron house and estate, with its "wonderful gardens and working farm".
"So there are additional attractions this year in addition to the usual things we've got on," she said.
"We've got a new science tent there's a Cwtsh Cymraeg which will be a welcoming place for Welsh learners and those interested in Welsh culture.
"We'll have a little train going round the maes and many more live performances this year. So there'll be lots of fun for everyone."
She said the eisteddfod had been good at developing as a festival rather than just focusing on the competitions.
There has been some criticism over the decision to serve alcohol in a restaurant at the event.
Ms Gruffudd Jones said visitors would be able to buy wine "in one small area of the site with their meal".
"So we'll see how it goes. We've always said it's an experiment and we'll be collecting the views of eisteddfodwyr [visitors to the event] throughout the week and we'll assess the situation as we go forwards to next year."
She said they understood the need to give young people the right signals about alcohol, but added: "We'll certainly be sending out a strong message that it's important to be sensible with alcohol and you'll only be able to purchase alcohol with a sit-down meal with waitress service.
"We'll have a host of other activities, so people will have all sorts of things to do all day at the eisteddfod."
There had been some water supply problems in recent days, and she said they had now been resolved.
The organiser, Urdd Gobaith Cymru, said it would welcome 15,000 competitors during the week.
Events include recitation, choral singing, dance, arts and craft, composition and poetry.