Ermoupolis is the most beautiful town on Syros. I loved the big, impressive buildings inspired by the Greek antiquity, with those tall columns and many floors. Time flew when I was shopping at the gift shops behing Miaouli square: great things to buy and good prices! Try Archontariki restaurant for nice baklava and when you leave the island buy loukoumia to offer to friends. Hermoupolis is also a nice base to go excursions. Definitely on Azolimnos and Galissas. Also go to Ano Syros, a vilage that looks like Ermoupolis a bit, only much smaller.