Since all of the attractions in Belem had closed, we headed up toward the main plaza (Plaza Mayor) of Lisbon, only to find that it had been torn up for reconstruction. Piles of little square stones lay on the torn up ground surrounding the plaza's fountain and statue. So we climbed onto a tram that took us up the steep hills of the Alfama district to find the Castle of St. George. (Seriously, if you want to visit Lisbon's castle, don't walk unless you like a strenous adventure. Not only are the streets extremely steep and windy and unmarked, but they are narrow as well and you share the road with the trams.)
We were happily surpised that the castle was so lively (also there was no price to pay for wandering). A huge beer festival had taken over the old walls. The outer courtyard was lined with booths selling Sagres Beer, several types (at least light & regular). Benches and tables filled up the interior. For about 1 USD, you got your very own plastic beer mug full of yummy rich malty grainy Spanish beer. The tapas they sold to accompany the beer was appalling overpriced. I think it was maybe 900 escudos for a plate of fatty sausage. They also had curried meat pies, and fish, and shish-kebabs. As you ventured further into the castle, you could gawk at the whimsical statues by a famous local artist. The interior courtyard of the castle was also full of beer festivities and as you wandered around, there were several displays set up showing how beer was made, and how popular Sagres beer was, and also about the origin of beer and some of the first beer drinkers -- monks.
After wandering around the castle's ruins (all its walls seem to be pretty much intact), we stood by the wall looking down in the harbor and watching the sun set. This was truly one of the most enjoyable experiences that we had in Lisbon.