You are standing in front of the Bibi-Khanym Mosque in Samarkand, a short walk north-east of the Registan. Face the entrance portal first. It is 35 metres high, and it was meant to make you feel small.

The mosque is named after Saray Mulk Khanym, the senior wife of Timur; "Bibi-Khanym" is a title of respect, roughly "the senior lady". Timur ordered the mosque after his campaign in India in 1399, and it was completed in 1404. It was to be the Friday mosque of his capital, large enough for the men of the whole city.

Walk through the portal into the courtyard and take in the plan. The outer walls measured 167 metres by 109 metres. Across the courtyard from the entrance stands the main sanctuary, with a dome about 40 metres high; two smaller domed halls face each other on the left and right. Galleries of columns once joined all four buildings around the court.

The builders worked at the limit of what brick could do, and the building began to fail almost at once. Within a few years bricks were falling from the great dome. Over the following centuries the mosque decayed into a ruin, and an earthquake in 1897 brought down more of it. What you see today is partly original and partly reconstruction: restoration began in 1974 and has continued in stages since. As you look, try to tell old brick from new.