Hagia Sophia in Istanbul’s old city is an architectural phenomenon and one of the largest enclosed spaces in the world. The central dome measures around 100 feet across and the scale of the internal space is overwhelming. Entrance costs 20 Turkish Lira*, (currently around £9). Don’t miss the selection of intricate mosaics in the gallery.

With detailed mosaics hanging in the gallery and a huge central dome measuring 100 feet across the Hagia Sophia is one of Istanbul’s Byzantine architectural highlights and instantly recognisable across the city. It’s well worth the £9 (or 20 Turkish Lira) entrance fee.