Berlin Cathedral audio guide,
five stops, free.

Stand on the paths near the fountain and let the whole front fill your view, because this is the side it was built to be seen from. The cathedral faces west, onto the Lustgarten, and everything about this face is meant to stop you: a two-storey front, a hall of columns, a granite staircase, and above it all a dome of green copper.

The ambition behind it was not modest. The cathedral itself describes the building as Emperor Wilhelm the Second's Berlin answer to Saint Peter's in Rome. The architect was Julius Carl Raschdorff, a Catholic from Silesia who had been city master builder in Cologne, which is a nice irony for the largest Protestant church in Germany. The foundation stone went down on the 17th of June 1894, with 1900 as the target. Delays pushed the opening to the 27th of February 1905. Raschdorff had to rework his plans more than once, not least after the Prussian parliament granted him only 10 of the 20 million marks he had hoped for.

Now look up at the dome, and then at the four towers, because what you are seeing is not quite what 1905 saw. In May 1944 the dome burned. When East Germany finally rebuilt the exterior, from 1975, the main dome and the tower tops came back in a much plainer form, each one 16 metres lower, with every lantern that crowned them removed and a completely new cross on top. The reason was political. The government did not want a fully restored monument of the Empire outshining its own new state buildings nearby, the Palace of the Republic among them. So the cathedral was 114 metres high when it opened and is 98 today.

The arched mosaic over the main door came late, in 1920, and the bronze doors below it in 1907. Notice too how dark the stone is. That is not age alone. The cathedral's own builders say soot, dust and rubber from the traffic settle on the sandstone, and air pollution mixed with rain forms acids that slowly eat into it.

The ground under your feet has had a busier life than the church. The Lustgarten began as the palace kitchen garden, became a formal pleasure garden in 1646, and in 1713 the soldier king Frederick William the First turned it into a sand-covered parade ground. The Nazis paved it over for mass rallies in 1934. Only at the end of the 1990s did it become a park again, and the fountain in front of you stands where Schinkel had planned one, on the spot where the first fountain here threw its water 13 metres high on the power of a steam engine.

Turn from the middle of the dome towards the east end, where the floor rises seven steps to the chancel. The cathedral calls this part particularly splendid, and it is the one place in the room where the Emperor's builders were happy to reuse the past. Most of what stands up there came from the older cathedral that was knocked down to make way for this one.

Start with the three tall windows behind the altar. The middle one is the Nativity, and on either side are the Crucifixion and the Resurrection. They are Anton von Werner's designs, but the glass is not his. In December 1940 the blast from a British air raid blew out these windows along with every other window in the building. Von Werner's designs survived, and the altar windows were remade to them, a job finished in 1999. So the colour falling on the altar is late twentieth century glass telling you exactly what the Emperor saw.

Now the altar itself, the white table at the top of the steps. It is marble with yellowish onyx, designed by Friedrich August Stüler and made in 1850 for the old cathedral, and it is a piece of theology in stone. It mixes a Lutheran block altar with a Reformed table altar, because this church stood for the union of the two Protestant traditions in Prussia. Behind it rises the gilded Apostles' Screen, designed by Karl Friedrich Schinkel. It was bronze to begin with and is now gilded all over, and the small apostles along it are copies of the figures on the tomb of Saint Sebald in Nuremberg. The two tall floor candelabra of gilded iron are Schinkel's too, modelled by the sculptor Theodor Kalide; Raschdorff had them made taller and added to for the new church. Behind the screen, in the baptismal area, stands a white marble font by Christian Daniel Rauch.

Then look to the side at the oak pulpit, designed by Otto Raschdorff, the architect's son, who worked in his father's office. It was one of the few things not ready for the opening and was only finished in 1908. Carved along it are the words Des Herrn Wort bleibet ewiglich, the Word of the Lord endures for ever.

Finally, the stone giants guarding this end of the church. On the altar side stand four-metre sandstone statues of the reformers, Luther, Melanchthon, Zwingli and Calvin. Face the other way and you will find their political counterparts, the four princes who backed the Reformation, gathered around the Emperor's own box. The reformers face the rulers across the room, which is the whole argument of this building in two rows of statues.

You have earned this one. You are on the walkway round the drum of the dome, 50 metres above the ground, and there is no glass between you and the city, only a wide balustrade. The cathedral says you can hear music being played down in the Lustgarten from here, and on a quiet day you can.

Start by finding the park you stood in at the beginning. It is due west, straight below you, a rectangle of lawns and paths, and the long colonnade along its right-hand, northern side is Schinkel's Altes Museum. Once, this was the palace kitchen garden, then a parade ground, then a paved rally square, and now it is a park again. Now look past the park, due west and a little under two kilometres away, for the Reichstag, one of the sights the cathedral names for this walk.

Now walk round to the east and north-east. The television tower is there, about 600 metres off, and a little to the right of it, due east, the red brick tower of the Rotes Rathaus, the city hall. Below you on the east side runs the Spree, with its tourist boats. To the south-south-east, very close, is the Humboldt Forum, standing on the site of the Berlin Palace. That neighbour explains the building you are standing on. The cathedral's story began as a chapel inside the palace, its crypt and tombs document five hundred years of the ruling family's burial customs, and the cathedral itself says it is still closely linked to the palace.

Then look up behind you at the dome itself. You are close now to the angels with their instruments that ring it. The dome above them is not the dome of 1905. After the fire of 1944 East Germany rebuilt it, lower and plainer, and the cathedral's own history admits that the shape of the dome had been argued over by architects since the day it was built. The plain version has now been protected as a monument in its own right, which makes any return to the old outline all the harder.

Finally, on the north side, look down at the edge of the building. Roughly a third of the cathedral as first laid out is missing, and this is where it was: the Memorial Church, a wing for the dynasty's ceremonial tombs, which was blown up on the 30th of October 1975. Some 204 of its carved facade stones were saved, and they still lie in a wood at Ahrensfelde. The cathedral's own description of the empty ground below you is an unattractive spot, and from up here you can see exactly what it means.