Enryakuji temple is a UNESCO World heritage located on Hieizan(Mt.Hiei) in Otsu, Shiga prefecture. Hieizan is located between Shiga and Kyoto prefecture and therefore it is possible to visit the temple from Kyoto city.
Japanese consider as Hieizan = Enryakuji. Therefore most of the Japanese call, Hieizan Enryakuji, rather than Enryakuji. Hieizan is one of the most sacred mountains in Japan, together with Koyasan(Mt.Koya) in Wakayama prefecture.
On the other hand, foreign tourists visit Enryakuji less than Koyasan. To access to Enryakuji is much easier than going to Koyasan. From Kyoto, you can take a train or bus to Eizan railways Eizanguchi station and take a funicular. Then, change to aerial tramway. Another route from Kyoto is to take JR Kosei line to Hieizan Sakamoto station and walk or take a bus to Sakamoto cable car. Then, you will reach the top of Hieizan and continue to Enryakuji on foot.
Just watch out that Enryakuji has several buildings around Hieizan and it is not next to each other. Therefore you can take the shuttle bus which you can hop on and hop off as much as you want(of course it is not free of charge).