It's a quick water taxi ride from Orta San Giulio to Isola di San Giulio. The basilica on the tiny island was first built in 926 but has had many revisions and renovations since then. It's part of an active Benedictine monastery.
Here's a brief history of the island.
Most interesting to me were the frescoes, which ranged in age from early medieval to Renaissance. This one, on a pillar, looked Byzantine in influence. I was sure I took more fresco photos, but I don't find them on my camera. Maybe I spaced out.
Here's a site with more photos of the frescoes.
A few more of my photos from the island on continuation page.
A view of the little island from San Guilio:
An alley leading down to the water:
A couple of old buildings on the island: