Any ideas of something I could do alone while in Athens?

Last time I came to Athens, I somewhat enjoyed myself but the biggest reason was because I came during the holiday time and I love Christmas decorations. All the Christmas stuff (Syntagma Square, visiting Hotel Grande Bretagne, etc) was super fun and lovely.

Doing non-holiday things just made me lonely (museums are okay but there's only so many I can go to...). Taking cruises was hard because the pictures were nice but I felt lonely. I'm in Athens now (the Athenian Riviera to be precise) for work. I really cannot think of what I can do here in my free time (I've been drowning in work to avoid going outside). Any ideas?