1 Hampi ruins, India
This jaw-dropping complex of ruins - the largest in India - was once the capital of the formidable Vijayanagara empire. It stretches over about nine square miles amid huge boulders and vegetation, its fabulous temples, palaces and ramparts reflecting the extraordinary wealth that was once concentrated here. From the carvings at the great Virupaksha temple to the huge elephant stables, most of the site was built between the 14th and 16th centuries.
The risk: Hampi is one of 33 sites on the Unesco List of World Heritage in Danger. This is because of the construction of two suspension bridges within the area. There is further concern over the building of a road bringing in heavy traffic.
How to get there: The ruins are remote: eight miles east of the little town of Hospet and about 215 miles (seven hours by car) north west of Bangalore, which is the most convenient international gateway. British Airways (0870 850 9850; ba.com) flies direct from Heathrow to Bangalore; return flights from £258. Trans Indus (020 8566 2729, transindus.com) offers an independent 16-day tour of Hampi and the Deccan Plateau from £1,998 per person, based on two sharing, including return flights, transfers and b&b.
2 Finca Vigia, Cuba
Built in 1886, this hilltop villa at San Francisco de Paula was home to Ernest Hemingway from 1940 to 1960. It was donated to the Cuban people after the author's death in 1961. It looks much as the Hemingways left it, containing thousands of books, works of art by Picasso and even, in the grounds, the fishing boat Pilar, immortalised in The Old Man and the Sea.
The risk: Having suffered structural problems due to the combined effects of humidity, hurricanes and ageing, the property was placed on the 2005 list of America's 11 Most Endangered Places, compiled by the US National Trust for Historic Preservation.
How to get there: San Francisco de Paula is a 20-minute drive from Havana. Tailor-made packages to Cuba, taking in the island's colonial heritage and more, can be arranged by Voyager Cuba (01580 766222; voyagercuba.co.uk) from £800 per person, based on two sharing in a two-week trip. The price includes return flights from Gatwick to Havana and b&b - where possible in heritage-style hotels. Visas, car hire and other transport can also be organised.
3 Abu Mena, Egypt
The early Christian city of Abu Mena was described in awestruck language by the 11th-century geographer Al-Bakri and other medieval visitors: it was said to have been built of marble and decorated with magnificent mosaics and statues. Its ruins were discovered in the Mariut Desert, south-west of Alexandria, in 1905 by the German archaeologist Carl Kaufmann. Subsequent excavations have revealed basilicas, baths, a church, a baptistry and workshops built over the shrine of Menas, a 3rd-century Christian martyr.
The risk: Irrigation has caused the water table to rise. As a result, a number of structures at Abu Mena have collapsed - and the site is now on the Unesco List of World Heritage in Danger. The damage continues despite efforts to dig trenches for water drainage and to expand the area under protection.
How to get there: The site is some 50 miles from Alexandria, which is a good base for visits. Audley Travel (01869 276 220; audleytravel.com) offers an independent seven-day trip in September, taking in Alexandria and Cairo and with a tour of Abu Mena and the synagogues and churches of Old Cairo (as well as the Sphinx and Pyramids). The price is £995 per person, based on two sharing, which includes return flights from Heathrow to Alexandria, first-class return train travel to Cairo, tours and b&b in four- and five-star hotels.
4 Saltpeter Works, Chile
The Humberstone and Santa Laura Saltpeter Works, in the Pampa desert of northern Chile, near Iquique, are industrial sites where thousands of people worked to extract the mineral saltpeter (sodium nitrate), used as a fertiliser throughout the world before the invention of synthetic nitrate. Both Humberstone and Santa Laura were built in 1872 and were declared national monuments in 1970.
The risk: The buildings at both sites were placed on Unesco's List of World Heritage in Danger last year partly because of a recent earthquake and partly because the constructions of timber and corrugated iron are now fragile. Little maintenance took place for about 40 years, and the buildings were subject to vandalism.
How to get there: The sites are just over a mile apart and can be reached from the city of Iquique, 32 miles away. Last Frontiers (01296 653000; lastfrontiers.com) offers a tour of both sites as part of a 10-day holiday. The price of £2,295 per person, based on two sharing, includes international and internal flights with LAN, tours, transfers and b&b, with two nights in Iquique, three nights in the Atacama Desert and three nights at Lauca National Park.
5 Semenovskoe-Otrada, Russia
The mansion of Semenovskoe-Otrada is a sublime example of 18th-century Classicism. It is set on an estate near Moscow that was founded by the brother of Count Grigory Orlov, Catherine the Great's co-conspirator in her plan to seize power. The building's interior was painted in 1830 by the famous Russian romantic artist Karl Brullov, while the gardens were laid out by the French landscape architect Édouard André.
The risk: At the time of the collapse of Russia's Communist regime in the 1990s, Semenovskoe-Otrada had been well restored. But it has since become almost derelict and prey to vandalism; it is one of a number of Russian country estates in jeopardy.
How to get there: The mansion is in Podmoskovie, an area of Moscow county that surrounds the actual city. Short city-break packages to the Russian capital include a three-night trip with Kirker Holidays (0870 421 1201; kirkerholidays.com) from £1,051 per person, based on two sharing. The price covers return flights from Heathrow to Moscow, tourist entrance visa and b&b at the five-star Metropole hotel as well as Kirker guide notes to restaurants and city sights.
6 Jvari Monastery, Georgia
Mtskheta was the ancient capital of Georgia and it remains the country's spiritual centre. Since 1994 it has been on the Unesco World Heritage List because of its churches. One of the greatest of these is the Jvari Monastery, standing on a hill above the old city. It consists of a collection of buildings, chief of which are the Small Church, built in 545, and the Great Church, a domed medieval masterpiece begun in 586.
The risk: Maintenance of the Jvari buildings has been very poor, and acid rain has eroded some of the stone. Inappropriate conservation work has also contributed to the damage. Part of the roof of the Small Church has collapsed, and the interior mosaics and frescoes have been largely destroyed by the elements.
How to get there: Mtskheta is about 16 miles from Georgia's modern capital, Tbilisi. Regent Holidays (0870 499 0911; regent-holidays.co.uk) offers short breaks to the city from £535 per person, based on two sharing, including return flights from Heathrow on British Mediterranean and three nights' b&b. The company can arrange daytrips from Tbilisi to take in Mtskheta and the Jvari Monastery as well as the nearby sights of Gori, birthplace of Stalin, and Uplistsikhe, a 6th-century cave town: the price, from £55 per person, includes car, guide and lunch.
7 Commonwealth Institute, UK
This is regarded as an outstanding example of post-war architecture, and one of London's most important public buildings of the 1960s. Designed by Sir Robert Matthew to be educational and user-friendly, it has a huge three-storey public exhibition space that was conceived to reflect the unity and diversity of the Commonwealth. The main building is a tent-like pavilion whose curved copper roof was a pioneering feat of engineering. Located in Kensington, the institute is a Grade II* listed building.
The risk: In spite of the completion of a £3m refurbishment in December 2001, the Commonwealth Institute is now empty. It occupies a prime site but remains protected and cannot be demolished because of its listed status. In July last year, an application to de-list the building was turned down by Tessa Jowell, the Culture Secretary. But earlier this month, a leak from the Foreign Office exposed government plans to introduce legislation to overturn the listing.
How to get there: The building is on Kensington High Street, south of Holland Park. The nearest Tube station is High Street Kensington.
8 Mehmed-Pasha Sokolovic Bridge
Built in the 1570s on the main route between Bosnia and Istanbul, the Mehmed-Pasha Sokolovic Bridge, in Bosnia/Herzegovina on the River Drina at Visegrad, is a Balkan icon. It was designed by Kodza Mimar Sinan, one of the greatest architects of the Ottoman empire, and its legendary status was confirmed in Ivo Andric's 1945 novel, The Bridge on the Drina. Its 11 arches have been much restored, particularly after damage in the two world wars.
The risk: The bridge is becoming unstable because of daily fluctuations in the Drina's water flow and level, caused by the construction of two hydroelectric power plants.
How to get there: Visegrad is about 60 miles east of Sarajevo, the nearest international gateway. Sarajevo is not easy, or cheap, to reach from the UK. Some of the best deals are offered by Czech Airlines (0870 444 3747; czechairlines.co.uk) via Prague, with return tickets from Heathrow around £250. For accommodation go to bhtourism.ba
Harriet O'Brien is author of "Queen Emma and the Vikings - The Woman Who Shaped the Events of 1066", published in paperback by Bloomsbury tomorrow, price £8.99
The best city centre
Italy rebuilt Asmara in the 1930s in a modernist style. A good 400 buildings remain, some with curving facades and bold stairwell towers. There is even a futuristic petrol station with cantilevered concrete wings.
The risk: Demand for new construction has put the city under pressure, despite government protection.
How to get there: Explore (0870 333 4001; explore.co.uk) offers nine-day trips starting in October, from £1,024.
The best village hall
Greenlaw Town Hall
This 1829 Greek Revival-style building, complete with cupola, pillars and pediments, was designed by John Cunningham. In 1904 it became redundant, and has since been used as a village hall, a billet for Polish prisoners and a swimming pool. It is now empty.
The risk: The state of disrepair is becoming acute: the roof is beginning to sag and dry rot is spreading.
How to get there: Follow the A697 in Scotland.