Ancient Tomb
Kofun
noun
An old tomb is an ancient tomb. They're mostly from the Kofun period, and indeed that's where the period gets its name.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
近年その古墳を訪れる人が増えています。
The number of people visiting the ancient tomb has been increasing in recent years.
このカフェでは、古墳の形をしたケーキが食べれます。
In this cafe, you can eat cakes in the shape of ancient tombs.
古川君は、古墳マニアなんですよ。
Furukawa-kun is ancient tomb enthusiast.
古墳時代は、三世紀末頃から七世紀頃までの時代を言います。
The Kofun period refers to the period from around the end of the 3rd century to the 7th century.