Learn Spanish (Latin America): Visitamos el edificio, alrededor del cual el jardín era hermoso. - We visited the building, around which the garden was beautiful.

In Spanish, you can't use the simple relative pronoun que after a compound preposition (a preposition made of more than one word, like alrededor de). You must use a complex relative pronoun like el cual or el que.

Could I use del que instead of del cual in this sentence?

Yes! ...alrededor del que... is perfectly correct and actually more common in everyday spoken Spanish. Using ...alrededor del cual... means the exact same thing but elevates the register, making it sound slightly more formal or literary.

Why does it combine into del cual rather than staying de el cual?

The relative pronoun el cual follows the preposition alrededor de. Just like in any other sentence, whenever the preposition de is followed directly by the masculine article el, they must contract into del. This contraction is mandatory.

How do I know whether to use del cual or de la cual here?