You can book a programmable tour, every half-hour, from mid-June to early September, from 11 a.m. to 4 p.m., [here].(https://sierrastateparks.org/emerald-bay-state-park/vikingsholm-tours/?utm_source=easyvoyage)
Tickets cost $15 per adult and $12 for young people aged 7 to 17, students with a university ID card, members of the armed forces on active service and senior citizens. Children under 7 are free, and tickets can also be purchased at the visitor centre.
Access is either on foot via a slightly steep path starting at Highway 89, the Vikingsholm Trail, or via another path starting at Eagle Point Campground Campfire centre.
Make sure you're physically up to making the return journey. It's uphill!
Dogs are not allowed, including on the 2 trails mentioned above.