It's hard to envisage today, but the Treadwell mine on Douglas Island was once the largest gold mine in the world, set up like a minitown with its own baseball diamond, stores, dormitories and blacksmith. Reaching its zenith in the 1880s, the mine was subsequently abandoned after part of it slid into the sea in 1917. Today, spooky reminders of Juneau's affluent mining past poke through the forest on this well-signposted historical trail with recently installed interpretive boards.
Of note is the concrete 'New Office Building', the 1917 slide site, a 'glory hole' and a restored pump house that stands like a beached tower a few meters offshore.
Treadwell is 3 miles south of the Douglas Bridge adjacent to Savikko Park. Buses 1 or 11 from downtown will get you there.