Beside the theatre sprawls an open-air cafe, canopied by a huge acacia tree, where patrons sip excellent local coffee at leisure. Standing high above the scene is a rough-hewn statue of a herdsman in a noble pose, seeming to say - in a country where pastoralists abound - 'I am the soul of Ethiopia'. Beside the boulevard is a huge modernist statue of a long-necked lion sporting a cascading mane of rectangular plates, as if armoured. A crown on its head, it is the Lion of Judah, symbol of the nation.

The once imperial capital of a very old country, Addis Ababa - meaning 'new flower' - was founded in the late 19th century on the high plateau that forms the heartland of Ethiopia. Here His Imperial Majesty Haile Selassie I - King of Kings, Lord of Lords, Conquering Lion of the Tribe of Judah, Elect of God and Power of the Trinity - ruled in archaic splendour for almost half a century, until he was deposed in 1974 by a brutal Marxist dictatorship. Exit the Lion of Judah, enter the Hyena of the Horn.

Mengistu Haile Mariam, the leader of the Derg revolution, ruled for 17 years and left his brutish mark on Addis Ababa. The granite Derg Monument on Churchill Avenue, the city's main drag, projects typical communist triumphalism in its huge sculpted tableaux, depicting the people steadfastly marching towards an inevitable utopia, led by the wise and wonderful dictator. You have to admire the bas-relief artistry, though, particularly the finely carved starving women, all of it fashioned by North Korean sculptors in an outpouring of comradeship.

The Derg may have left a heavy bootprint but Haile Selassie ruled three times longer than them, and represented a millennial tradition. Visitors can get some sense of his Ruritanian reign - brilliantly captured by Ryszard Kapuscinski in his book The Emperor - by trekking out to Addis Ababa University, the main building of which served as the living deity's palace. In Genete Le'ul, the Princely Garden Palace, the powder blue bathroom is state-of-the-art circa 1930s and the bed conjures up the French Second Empire. The emperor's pet lions used to roam these gardens.

His throne, in white ebony with huge arms shaped like standing lions, is not here, nor is it in his enormous third palace, finished in 1955. Instead, the throne sits in the Holy Trinity Cathedral, the second ranking church in the world's second oldest Christian nation. Here Haile Selassie's remains were finally entombed in 2000, after a quarter of a century of travails caused by the Derg. Built in an engagingly eclectic style you might call 'Ethio-Baroque' and consecrated in 1942, the Holy Trinity's white stone facade is draped with 20-metre long, red-yellow-green tricolours. These are the national colours of Ethiopia, as any Rastafarian or reggae fan could tell you. The colours appear everywhere, in many forms, and remind us that - to his great bemusement when he was alive - Haile Selassie is worshipped by Rastas as God incarnate.

Addis Ababa made the most of the African independence days. Though Ethiopia was the only African country never to be colonised, except for the brief and bloody Italian intervention (1935-41), black Africa's oldest nation wholeheartedly joined in the joy of its fellow Africans. The city hosted the headquarters of the new Organisation of African Unity (now the African Union) and a major United Nations conference centre. As another UN venue, Haile Selassie also built the dazzling Africa Hall.

Revealing how times have moved on, my taxi driver hasn't heard of it. Roughly in the vicinity, we rattle up and down an immensely wide dual carriageway flanked by eucalyptus and casuarina copses with no sign of a grand hall. I look for an escape. The map says the Hilton is coming up on the left, and, suddenly, there it appears, up on a wooded hill in glorious isolation. A sanctuary.

The Addis Ababa Hilton is not just another anonymous five-star, but an African icon. For decades, this was the only public piece of Western efficiency and luxury in the whole capital city, or nation, for that matter. Even now, it is not so much a hotel as a refuge for expats and executives, where they can find such rare pleasures as an ATM machine, a gym and a reliable internet connection.

With Addis Ababa a political hub for Africa, the hotel has welcomed just about every African ruler over the past half century; the good, the bad and the atrocious. In a city that has hosted innumerable pan-African conferences and crisis meetings, the Hilton has been the hostelry of choice for all the Kenyattas and Kaundas, the Nkrumahs and Nyereres, and - 'what the hell, we're just a hotel' - the Mobutus and Mugabes. In 1998, however, a Sheraton arrived and usurped the role of top luxury hotel, an oasis of opulence where distinguished men in long robes from far corners of Africa flick ornate fly-whisks and command instant obedience.

Africa Hall, surely the Hilton concierge knows it? Yes he does, but you can't go there, he says, except on official business, so its gigantic stained-glass window - an outstanding sight of modern Africa - is beyond reach. Measuring 150 square metres, its storied panels represent Africa past, with much blood red; Africa present, featuring fertile green; and Africa future, dominated by a sunny yellow.

The highlight of the building in which the African Union was founded, the window was created by Ethiopian artist Afewerk Tekle and called Total Liberation of Africa, which this year has a special irony. Exactly half a century later, a newly opened African Union headquarters dominates the skyline of Addis Ababa. The city's tallest building, at 100 metres high, was built not by Africans, though - but by China. A gift to Africa, most of the materials used, including the furnishings, were imported from China.

The irony? In many parts of Africa, you are not considered a man until you build your own home.