Founded by Peter the Great in 1710, this orthodox monastery is the most important in St. Petersburg. The St. Trinity cathedral is worth a visit and so is the cemetery, where you can visit the graves of Russia's greatest composers and writers, including Tchaikovsky, Mussorgsky, Glinka and Dostoevsky. You can buy fresh holy bread in the monastery's bakery in the afternoon (on your left as you approach the Trinity cathedral from the entrance).