In the heart of Amsterdam the English Reformed Church was built in 1419 for the Catholic sisterhood sanctuary known as the Bengijntjes for single women who did not take monastic vows but educated the poor and took care of the sick. The church was turned to a Protestant denomination following the Alteration in 1578.
The church is in the center, or courtyard, of a block of houses. I love the little chapel across the lawn with the stain glass.
Also in this area you will see the Het Houten Huis - No. 34 - which is the oldest building in Amsterdam from around 1420 and one of the two remaining all wooden structures/buildings in Amsterdam since the city banned wooden buildings in 1521 due to devastating fires and also since most of the buildings in the Begijnhof were not built until after the 1500's.
Another truly magnificent spot just north of Vondelpark is Hollandsche Mangege, or the Netherlands Horse School. I wish I was able to add more photos or I would as this building is really beautiful.
It opened in 1882 and was designed after the Spanish Riding School in Vienna. In the early 1980's the building, and school, were threatened with demolition but due to a major outcry from its neighbors, funds were raised and the school continues today.
Amsterdam can be a hard place to warm up to. It is one of the most beautiful but the people are somewhat distant and cold. Give them and the city time and it's warmth will come.
Read my experiences of Amsterdam in my link below.