The panoramic views from Asen's Fortress, which squats precariously on the edge of a cliff 19km southeast of Plovdiv, will make your stomach flutter. Early incarnations of the structure were bulked up by Thracians in the 5th century BC. Over the centuries, Roman, Byzantine and Ottoman rulers admired its impenetrable position so much that they continued to build and rebuild, adding chapels and thickening its walls to a battering-ram-proof 3m. It's signposted ('Asenova Krepost') off route 86.
Buses run half-hourly from Plovdiv's Rodopi bus station to Assenovgrad (2 lv, 30 minutes); from here, hail a taxi to the fortress. Taxis from Plovdiv will charge about 40 lv for a return trip to the fortress.
