The Monolith Tour was a concert tour by American rock band Thirty Seconds to Mars. Staged in support of the band's fifth studio album America (2018), the tour visited arenas and stadiums throughout 2018 and 2019. It was initially announced in October 2017 with European dates being released at the same time, with North American dates announced afterwards. It began on March 12, 2018 in Basel, Switzerland, and concluded on August 17, 2019 in Großpösna, Germany. The support acts for the tour included Walk the Moon, K.Flay, MisterWives, Joywave, and Welshly Arms.

Thirty Seconds to Mars is an American rock band from Los Angeles, California, formed in 1998. The band consists of brothers Jared Leto and Shannon Leto. During the course of its existence, it has undergone various line-up changes with the Leto brothers being the only consistent members.