It is the trams I like most about Vienna. They are the single most valuable tools the city offers residents and visitors alike.

There is an ever-expanding network, and bus routes where neither trams nor underground run; but the wooden-seated, red-and-yellow Wiener Linien trams are like arteries, carrying people almost anywhere and everywhere.From May day onward, through spring and summer, the trams roll around the city with a celebratory cluster of small red-and-white flags on the roof above each driver's head.

In spite of there being 35 lines and 991 stops in a city of only 1.5 million people, there are so many trams that for most of the day you rarely wait more than three minutes for the next to come along.

They are also cheap, to encourage people to use public transport. It works as passenger numbers rose 36 percent against 15 percent for car ownership in one recent 10-year period.

I have lived in Vienna for periods from days to months during the past seven years and used all types of tickets, which can be bought from Vienna's proliferation of tobacco shops, kiosks and news-stands. I have virtually given up driving in the city. The one-way system is easy once mastered, but parking is a nightmare.

Instead, I have come to love the tram. Even though the city center is entirely walkable, the No. 1 and 2 trams circumnavigate it continuously, traveling the Ringstrasse in opposite directions.

Hopping on and off a No. 1 or 2 is a sensible way of saving one's legs for more serious walking at important places around the Ring, such as the Kunsthistorisches Museum to see, among other things, Klimt's famous frieze, or the Hofburg Palace and Rathaus, the Opera, the Secession modern art gallery, the Karlskirche or the Stadtpark, a sculpture garden for Vienna's famous composers, where an orchestra plays Strauss waltzes on summer afternoons.

The N tram - some have numbers, some letters - travels to the Hundertwasserhaus municipal housing complex, which has revolutionized much architectural design. The D goes past the Karl-Marx-Hof workers' flats in the suburb of Heiligenstadt, shelled by government troops in the 1930s in Vienna's own war between fascism and the left.

You should get off the N to explore the astonishing Hun-dert-was-ser-haus, but the uninspiringly uniform Karl-Marx-Hof is just as well viewed from a passing tram. Better to stay on the D to the terminus five minutes away in Nussdorf. At the foot of the Kahlenberg mountain and on the edge of the Vienna woods, Nussdorf is where Beethoven finished the Ninth. There is a stream to stroll by into the woods, but - more important - a large number of heurigen, which are inns attached to vineyards, the Viennese equivalent of pubs.

Forget the cafe society: though the Zentrale, Demels, Cafe Landt-mann and the Griensteidl are all among my favorites, they can be precious and expensive; the heuriger, with its simple tables and benches inside and out and its occasional live oompah or accordion music, will always typify the real Vienna to me.

Food is from the buffet and traditional - overdone roast pork, spare ribs, sausages, pickles, minced-meat or spinach tarts, overdressed salads, hot sauerkraut with bacon bits, with apple strudel and Schlag (cream) to follow - but it always tastes fine in a heuriger, probably because the local white wine, Gruner veltliner, comes by the viertel, or quarter-liter. travels particularly well between cup and lip and goes down like water.

The tram makes a good night or Sunday afternoon at a heuriger possible, with no fears of having to drive afterward. Alternatives to Nussdorf include Grinzing, at the No 38 tram terminus, and Stamm-ers-dorf, a wine-growing village across the Danube served by the No 31 tram, where heurigen come by the kilometer.