Taking place just before Lent in late February/early March, the carnival climaxes on Rosenmontag ('Rose Monday' -the 42nd day before Easter!), with early celebrations beginning the previous Thursday (Altweiberfastnacht) when tradition allows women to cut off mens' ties and to kiss any man she chooses! The official end is then on the Tuesday (Veilchendienstag) before Ash Wednesday, when tradition requires particiants to burn the spirit of carnival to atone for ones sins committed during the carnival season (Nubbelverbrennung)!
On Rosenmontag itself there are Rosenmontagzuege (Rose Monday parades) during which the 1km-long carnival train passes through the streets and everyone everywhere gets dressed up in weird and wonderful costumes (be warned - you'll be the odd one out if you don't!). As the colourful floats pass by amidst singing of old Karneval songs and tunes, the costumed figures aboard traditionally through sweets, bunches of flowers and small gifts into the crowds around them.
The Karneval takes place annually and is a great, colourful and fun (if rather crowded!) occasion. Closing times for pubs and bars are suspended for the duration of the celebrations, which means that street party continues inside until the very small hours!