I couldn’t recommend it enough!
The free Plovdiv tour was excellent! I had arrived a few hours earlier, and my friend suggested I check it out. Our host Adi was friendly, knowledgeable and spoke English very well, along with Russian German and of course Bulgarian. Very impressed. The city is all easily reached on foot, and we saw some fascinating sights like the recently discovered Roman ampitheatre. You’d be crazy not to check it out.