Alhambra audio guide,
five stops, free.

You have just walked up through the wood, and this is the way the Alhambra was meant to be entered. The square tower in front of you, with the tall brick horseshoe arch cut into it, is the Gate of Justice, built in 1348 under Sultan Yusuf the First. Of the four gates in the Alhambra's outer walls it is the largest, and the Patronato that runs the site today calls it the most monumental. Its Arabic name was Bab al-Shari'a, the Gate of the Law.

Look up at the keystone of the great arch. There is a hand carved on it, five fingers spread. The usual reading is that the fingers stand for the Five Pillars of Islam, and the hand itself is read as a sign of welcome, and a charm against the evil eye. Now look through the arch, into the shadow, at the smaller inner arch behind it. On that one there is a key.

Above the key runs a band of Arabic script. That is the foundation inscription, and it names the gate and gives the dates it was finished, between the thirtieth of May and the twenty-eighth of June 1348. And above the inscription, in a niche, sits something that was never meant to be there: a Gothic Virgin and Child by Roberto Alemán, placed there on the orders of the Catholic Monarchs, Ferdinand and Isabella, after they took Granada. You are looking at the conquest, in stone, in a single doorway.

The door still has its iron-plated leaves and its original ironwork, and the four columns framing it carry the Muslim profession of faith on their capitals. Go through, and the passage will not let you walk straight in. It turns ninety degrees to the left, then ninety degrees to the right, up a steep ramp, with an opening overhead from which defenders could drop things on anyone forcing the way. The vaults inside are painted with red imitation brickwork, a Nasrid habit you will see again.

For over three hundred years this tower was also somebody's house. From the conquest in 1492 until Napoleon's troops arrived in 1810 it was the official home of the Alhambra's gatekeeper.

Before you go in, turn left. Against the wall below the round artillery bastion is the Pilar de Carlos V, a Renaissance fountain of 1524 with three stone masks spouting water, which the Patronato reads as Granada's three rivers. And one more thing about the colour of everything around you. Alhambra comes from the Arabic al-Hamra, the red one, because these walls are rammed earth made from a local clay full of iron oxide. The red you are standing among is the name.

Stand at the end of the pool and look down the length of it before you look at anything else. The water is doing a job. The whole south portico, seven arches and the wall above them, hangs upside down in it, and the Patronato describes the pool exactly that way: a mirror that breaks the flat horizontal lines of the court. The pool is 34 metres long in a courtyard 36.6 metres long, and the myrtle hedges along both sides give the place its name.

Now look at your feet. There is a small round fountain here, and a short channel from it into the pool. That channel is built so the water slows and pauses before it enters, so no ripple ever spoils the reflection. A whole courtyard designed around a still surface.

This was the heart of the Comares Palace, the official palace of the Nasrid sultans. Isma'il the First began it early in the fourteenth century, and Muhammad the Fifth gave it its final look in the 1360s. In a Hispano-Muslim house, the Patronato says, you could not tell a family's wealth from the outside; you found out in the courtyard. A palace was the same idea on a bigger scale.

Behind you is the Comares Tower, 45 metres high, the tallest in the Alhambra. Behind the portico at your back, filling the tower, lies the largest room in the whole complex, the Hall of the Ambassadors, the sultan's throne room. It is a square hall eleven point three metres square and eighteen point two metres high, and its ceiling is built from 8017 interlocking pieces of wood, a pattern read as the seven heavens. It was in that hall, in 1492, that Christopher Columbus put his plans for the Atlantic crossing to Ferdinand and Isabella. The contract itself was signed on the seventeenth of April, not here but at Santa Fe, outside Granada. When later Spanish kings came to stay, their flag flew from this tower rather than from the Alcazaba's watchtower.

Then turn back to the far end. The facade above the south portico is standing on its own. The halls behind it were demolished in the sixteenth century to make room for the Palace of Charles V, and the builders kept only this face, so the courtyard would still look complete from here. You can see the Emperor's stone wall showing above the roofline.

One last thing. The walls around you are carved stucco and the colours have gone, but they were painted in red, blue and gold, and among the carving are poems composed for the palace by the court poet and vizier Ibn Zamrak.

This is where the sultans came to get away from the Alhambra. The Generalife was their country estate, outside the walls and across the ravine, a retreat and a working farm at the same time. It was most likely built at the end of the thirteenth century or the very beginning of the fourteenth, and Isma'il the First had it redecorated in 1319.

The courtyard in front of you is long and narrow on purpose: 48.7 metres by 12.8, about four times as long as it is wide. Down the middle runs the water, and that water has come a long way. It is the Acequia Real, the Royal Canal, which takes its water from the river Darro about 6.1 kilometres to the east and feeds the whole monument, the fountains you have already seen included.

Now the surprise. Those arching jets crossing the channel, copied in gardens all over the world, are not Nasrid at all. They were put in during the nineteenth century. When archaeologists dug here after a fire in 1958, they found the channel had once had twelve spouts, and they found the original Moorish paths and garden soil about 70 centimetres below the flowerbeds you are looking at. Then they covered it all up again and replanted.

Look along the left-hand side, the west. It was once a high blank wall, and this was a closed, private garden looking only inwards. After the conquest the wall was lowered and an arcaded gallery built along it, and if you look inside those arches you can find the Catholic Monarchs' badges painted there, the yoke and the arrows, with their motto, Tanto Monta. In the middle of that side is a small projecting room, the mirador, probably the court's only original window on the world. Its windows sit low because people sat on the floor, an arm on the sill, looking out over the gardens to the Alhambra hill and the city below. The stucco inside is from Isma'il the First's reign, laid over older work.

At the far end, the north pavilion: five arches of carved stucco with bands of inscription, and through the middle one, if you line yourself up, the arch of another mirador beyond. The open gallery on the floor above it was added by Ferdinand and Isabella in 1494.

When the Venetian ambassador Andrea Navagero came here in 1526 he wrote about a fountain that threw water ten fathoms into the air. From here the way out is the Walk of the Oleanders and the Promenade of the Cypress Trees, and through the windows of the gallery on your left, across the valley, the red walls of the hill you have just walked the length of.