All these galleries are very nice, but let's be honest, on their own they're not worth traipsing halfway around the world for. However, the Unesco-protected old city of San'a is a different matter altogether. It would be fair to say that old San'a is one of the most beautiful cities anywhere on Earth and nothing is likely to prepare you for the moment you first pass through the gates of the Bab al-Yaman.

Most people spend days wandering without aim through this enormous work of art and that's certainly the best way to absorb this city. A compulsory activity for tourist and local alike is to climb to the top of one of the tower houses and relish the ravishing views over the city as the sun sinks below the surrounding mountains. San'a is so perfectly preserved that it is said you can walk a square kilometre in any direction without encountering a single new building. The old city is particularly famous for its 'tower houses'. Reaching up to six or eight storeys, they have been called 'the world's first skyscrapers'; San'a contains no less than 14,000 of them. Tower houses tend to follow a set design: on the ground floor are the stables and storerooms; on the 1st floor the rooms used for entertaining; the 2nd floor is usually reserved for the women and children; and on the 3rd and 4th floors are the bedrooms, bathrooms and kitchen. At the very top of the house is the manzar (attic), which contains the mafraj (literally 'room with a view'). Serving often as windows in the mafraj, are moon-shaped, stained-glass windows known as qamariyas. Today much qat-chewing takes place here. The ground and 1st floors of the building are generally constructed of stone, and the upper levels of mud brick. Considered the best insulator in the world, the mud keeps the interior cool during the warmth of the day and warm during the cool of the night. Outside, the façade is whitewashed with lime (which protects the mud from rainwater) and decorated with geometrically patterned lines. The stone foundations of some houses are thought to date back at least a thousand years (the oldest building in the city was constructed a staggering two thousand years ago). The original plan and pattern of the San'a tower house is said to have come form the legendry Palace of Ghumdan a 2nd-century masterpiece, whose lights could be seen in Madinah, 1000km to the north, and which was said to have been as close to heaven as you could come on earth. The Great Mosque is thought to have been partially constructed with materials from this palace. Finally, the city may not look like a lush and green place, but while exploring old San'a keep an eye peeled for the hidden communal vegetable gardens that once made the city self-sufficient.