Think of Germany's capital as Europe's 'newest old city' and you'll have some idea of what to expect when you come here. Finally reunited as the last century drew to a close, Berlin today mirrors a convergence of contemporary lifestyles in an historic city that also has generous open space and recreation for urban dwellers. So whether you decide to play hard or easy, the options around Berlin are wide - from spa and fitness to forests and lakes that are a vital part of its urban landscape.

While Berlin remains among Europe's youngest, most lively capitals right now, with over 6,000 pubs within the city's limits, there are plentiful forms of entertainment not only after hours but just about any time. At the same time, with the sheer variety of healthful things to do here, it's also one of the most memorable sides of experiencing Berlin. Whether you've only got a few days or as much as a week, the city's many different active options, the many different choices offer something for every level of energy and interest.

Dedicated bike lanes line most Berlin streets, making it a practical way get around in a cardio-fit fashion, but the city's extensive parks and lake areas also provide ample routes for the biking enthusiast to pedal around the sprawling urban/rural mix. One of the best-equipped bike rental operators is Fahradstation, which has several city-wide locations (but phone ahead to reserve). If you've got at least half a day, this outfit also runs bike tours as far out as Potsdam and the eastern lakes. Interested in participating in a big-time local sports happening?

If inline skating is one of your activities, then a more frequent event to be a part of is 'Blade Night', which happens from spring to August every second Wednesday of the month. Streets in the central downtown are closed off to traffic for the evening, and rollerbladers take over the heart of the metropolis (during October to April, though, this happens indoors at Arena concert hall (Eichenstrasse 4 in Treptow).

On the other hand, if you'd also like to be out and about without wheels or crowds of any kind, then this city's many green areas, Spree river and canal banks provide plenty of space. The Tiergarten, close to the government quarter, is especially popular with joggers.

Berlin is an amazingly aquatic city, with some 120 sailing and 56 rowing associations, many of which offer day membership rates for visitors. The Berlin and Brandenburg lakes together make up the largest connected water area in Europe, and water sports of all kinds make up an equally large part of many Berliners' lifestyle. Right into September, locals and visitors are out and about on motor boats, yachts, mingling with surfers and canoe paddlers on the Wannsee, Havel or Spree.

I visited the huge Wannsee in western Berlin on a breezy but sunny late September day and lucked into the middle of a sailing regatta, while on other parts of the lake there were plenty of other craft bouncing on the waves, from paddle boats to canoes to windsurfers and jetskiers.

Berlin's better known central and western districts such as Charlottenburg, Prenzlauerberg or Mitte may still lead the way as far as best developed and numerous facilities, from indoor workouts at Gold's Gym to horseback riding to sailing and windsurfing, but you should consider at least a visit into the former East Berlin district of Koepenick, which contains a huge lake called the Moeggelsee. The shoreline along the Moeggelsee has plenty of both aquatic and land based activity, including sailing and boat rentals, windsurf and kayak rentals, and biking and rollerblade rentals; scenery and sport draw local Berliners and travelers alike from all generations, each taking advantage of the summer or fall seasons for an outing by the water.

And if you're here during the winter months, Berlin also offers some five ski slopes to practice your parallels on, and if there's been sufficient snowfall, you can hook up for lessons on the Teufelsberg, Berlin's own man-made mountain.

Berlin's Olympia Stadion is probably one of the most famous Olympic stadium sites as the arena for the 1936 Games. Walk around inside this landmark of massive Neoclassical architecture, imagine the crowds roaring as Jesse Owens surges forward into history, and gaze at the names of all the Olympic medalists inscribed on the walls and the huge statues outside. The stadium is still very much in use, so if you check ahead you may be lucky enough to time your visit with an actual sports event.

For something more recent though, you can always take part in one the more popular spectator sports that happen at various times throughout the year, from ice hockey to soccer to sailing regattas. You could try to be here during an event like the Berlin Marathon, which takes place every September -- some 27,000 runners from around the globe took part in the latest one.

With its super-efficient subway system, Berlin is a great city for exploring from one end to the other at any time of the year. You hear it from locals and travelers alike -- Berlin is changing fast, fast, fast -- in other words, visit soon while there's still time to witness the change and see what this metropolis was like in the early 21st century.