English Translation
We climbed to the top.
てっぺん is sometimes spelled 天辺. 天 means “sky”, so we describe the top of a mountain of a skyscraper as “around the sky”.
You can also use てっぺん metaphorically. For example,
彼は組織のてっぺんまで上り詰めた。（かれはそしきのてっぺんまでのぼりつめた）
means “he climbed the career ladder at the organization, and he assumes the most executive role now”.
Be careful. 上 can be pronounced あがる or のぼる when proceeded by てっぺん. あがる is used for the top of a building by an elevator etc. (i.e. automatic) while のぼる is done by your own effort (e.g. going up to the top on foot or climbing up the career ladder by yourself).