Went there last November. Took a tour of the Tweede Maasvlakte http://www.maasvlakte2.com/nl/home/
There are tours and water taxis to take to more harbours within the city.
Not all of the city was reconstructed so you will still find some parts completely untouched after the bombings of WW2. These locations with the newer architecture makes for an interesting city. Well that is my view and I do hope you take some time out to visit Rotterdam.
http://en.rotterdam.info/visitors/

Of course, I respect everyone's opinion and welcome lots of opinions from lots of people.

Whilts Rotterdam is not a must for most tourists it is certainly worth a visit imho. It offers something completely different to the main tourist honeypots. There is plenty to do there, from visiting museums, enjoying the modern and old architecture to the Euromast and boat trips around the harbour.

The train to Alkmaar takes between 1hr 27minutes and 1hr 42, depending on te trains taken. You have to go through Amsterdam to get from one to the other. Be careful of which train you choose though. The Thalys goes over that route and must be reserved, the Fyra, also a highspeed train, has a surcharge on it, and can be reserved. The normal slower IC trains have no surcharges and you take your chance on a seat - though that isn't normally a problem.

Rotterdam is one of the world's three busiest harbours and a tour of the vast docklands will fascinate anyone interested in marine commerce. There are museum displays oriented to naval history too, including floating examples of old vessels. The tours are limited to only the inner harbour in the off-season.
The city's bomb-flattened core is still being redeveloped and serves as a workshop for architectural and urban-planning experiments. More intimately, the restaurants and "brown" cafes are very hospitable for both dining and an exploration of Low Countries beer (most of the craft brews come from Belgium now.) I had a great time there.

I hve visited Rotterdam many times and find it one of the most unique and fascinating cities in Europe - if into museums it has several stellar ones, including a maritime museum and acclaimed modern art and architecture museum.

No not your old dreamy Dutch city but a modern town with great modern architecture all around - Delftshaven however retains its ancient look from times when the Pilgrims departed from her to the New World -

Alkmmar IMO is similar to Delft and Leiden as really old looking towns - Delft may though be more thoroughly old.

Definitely not a must IMHO, but if you have lots of time and will be nearby, worth a side trip.

So greekness2004 after this post and ones on other forums what is your opinion? Can you be bothered to find out what it is like or find somewhere more on the beaten track?

Rotterdam is worth a trip, the post WW2 arcitecture is cool, there is the walk of fame and a great bridge. We made a trip back to the netherlands just to see Rotterdam in person and not from a tour bus.

Yeh the walk of fame is right near the fantastic IMO Maritime Museum - there is some kind of playhouse it seems on the waterfront that attracts famous stars from around the world - they put their hand (foot?) prints in cement just like in Hollywood - though the cement on many was deteriorating when I was last there four years ago.

But Rotterdam yes - not your average cute old Dutch towns but a modern vibrant town filled with IMO stunning new architecture.

greekness2004 has now gone on to ask about Portugal maybe he is thinking about there now rather than NL, but who knows?