Old architecture, Utrecht
This castle is build in the late 19th century, it replaced a old former castle. In the grounds used to be a village, but it has been rebuild, and the village, called Haarzuilen is a nice little one. There is a café there, where you can have lunch.
The grounds are great too, but be awere, you have to pay to get in, and no sorry I do not how much.
If you go on a cycling tour, and take the Haarzuilen route, you will pass many nice little villages, and see a lot of rural Holland. The highlight of this tour is the castle, you can visit the grounds, and in the winter you can take a tour
In the Lombok neighbourhood, behind the station, you can find windmill De Ster which was built in 1721. A rebuilt was completed in 1999. De Ster was used as a sawmill until 1911, when more modern ways had become available. In 1982 the firm closed, but all the buildings that belonged to the mill have been preserved and are now used for various (cultural) purposes. The windmill itself can be visited on Saturdays from 13.00 until 16.00. Admission is free. There's another windmill closer to the centre but I can't say anything about that one.
The post-office is not easily missed, but many people will forget to take a closer look at this highlight of Amsterdam School architecture. Also take a look inside, it's well worth it!