Two ancient sites in Bulgaria. Amphitheatre of Serdica has no online ticket listed; Perperikon has 3 tickets and tours to book. The table and the two notes below put them side by side; the full pages have what to see, the ticket and the timing for each.
The Amphitheatre of Serdica is a Roman arena of the late 3rd and early 4th centuries AD, found by accident in 2004 under central Sofia. It was the largest amphitheatre in what is now Bulgaria, with seats for more than 20,000, and its eastern gate and part of the arena now sit inside a hotel lobby, open to visitors free of charge.
Perperikon is a rock-cut sanctuary and fortified city on a 470-metre hill in the Eastern Rhodopes, 15 km north-east of Kardzhali in southern Bulgaria. People used the summit from the Bronze Age to the Middle Ages, carving rooms, altars, stairs and wine troughs straight into the bedrock, and it is the largest megalithic complex in the Balkans.