"The temple is next to the synagogue."
Translation:Der Tempel steht neben der Synagoge.
two questions earlier it was "die" synagogue...which is it die or der?
It's a feminine noun, so it's die Synagoge. That said, neben causes the following noun to take the dative case (usually), so it becomes der Synagoge.
Most German prepositions change the case of the following noun. Here's a list:
Have you been reading the grammar tips and notes before each lesson?