I will be in Amsterdam for one week and plan to visit Rotterdam for a day trip to see the contrast between the cities. I want to rent a bicycle to tour the city and see the modern architecture. Any suggestions or highlights I should be sure to see?

In order to waste no time once in R'dam, go directly to the NAI. They have special maps with the modern architecture points of interest.

See http://en.nai.nl/

Thank you. What a fast response! Do you know if the NAI is near the Central Station?

All the detail are on the website, including a map.

You shouls also see the Erasmus Bridge, Kop van Zuid and the famous Cube houses.

This is also a great site for modern architecture:
http://tinyurl.com/6qn5yb

You can hire a bike at Rotterdam CS.

You can easily walk to the NAi from Centraal Station. I would recommend also visiting the Museum Boijmans van Beuningen which is across the street (for the art, though the building is good too).

If you want an excellent Rotterdam Architectural guidebook, when you arrive in NL visit any decent bookstore and ask for the Rotterdam Architectural guide published by 010. I've included the link below, but the website didn't allow me to link to the specific page. For the record, there is also an "all-Netherlands" version too, so you might want that.

www.010publishers.nl

The modern architectural highlights of Rotterdam are really too numerous to list, but Hetismij is on the money.

If architecture is your passion, go to Arcam in Amsterdam and you can find tonns of info including self-guided tour maps. Or, if you rent a bike from Macbikes, ask for the architecture map; the tours are self guided and will last either a full or half-day, taking in highlights and giving you a decent city tour also.

Lastly, if you find yourself in Utrecht, look into visiting the Centraal Museum and Rietveld-Schroder House. The Museum has alot of Gerrit Rietveld stuff, and the iconic house can be visited too.

Yes you should visit the Rietveld-Scroder house. And maybe drop into Hilversum for some Dudok - the town hall is a classic.

I did a day trip from Amsterdam to Rotterdam, or Manhattan on the Maas as i learned they call it as well due to its many new stall buildings built in bundles

and i visited several museums including the NAi and Museum Boijmans van Beuningen - both near each other as well as a row of houses opposite them that are also by Ritveld i believe or at least the Rotterdam school of that - the houses were built in the 20s and still look modern.

Buy a Museum Pass i suggest as it's good for all the Rotterdam museums and many in Amsterdam as well.

At the old port near the town center there is a Naval Museum or Boat Museum in old docks buildings with old trains, etc. outside

Near it is Rotterdam's Hollywood-like Walk of Fame where many celebrities have put their hands in cement and left their marks - practically every famous musical celebrity has done so - a very impressive roster documenting how Rotterdam is a mecca for music, etc.

I did this all with a fairly short few-mile walk. I would say ditch the bike and head right for the museum area - all are in a compact area.