In the 2000s, Richard Serra's art continued to evolve and expand, further cementing his position as a pivotal figure in contemporary sculpture. During this period, Serra further explored the possibilities of Corten steel, creating large-scale sculptures that engaged deeply with their environments and the viewers' physical experience of space. A significant highlight from this era is "The Matter of Time," a monumental installation at the Guggenheim Bilbao, unveiled in 2005. This work consists of a series of torqued spirals and ellipses that invite the viewer to walk through them, experiencing a range of psychological and physical states. The installation exemplifies Serra's interest in how sculpture can alter perception and engage the viewer in a dialogue with space​ (Metropolis Magazine)​. Another critical aspect of Serra's work during the 2000s is his continued exploration of site-specificity and the physical properties of his chosen materials. His sculptures from this period are noted for their ability to transform the viewer's experience of the surrounding space, making them active participants in the work rather than passive observers. This engagement with the viewer's physical presence and movement through space has been a hallmark of Serra's work, underscoring his belief in the sculpture as a phenomenological experience of weight, gravity, space, process, and time​ (Encyclopedia Britannica)​. Serra's works from the 2000s also maintained a focus on the minimalist aesthetic, emphasizing the materiality of the sculptures and their relationship to the environment. Despite their massive scale and imposing presence, Serra's sculptures from this era are meticulously designed to encourage contemplation and interaction, inviting viewers to reconsider their relationship to the physical world. Richard Serra's work in the 2000s continued to push the boundaries of sculpture, challenging viewers to engage with his works in a deeply physical and contemplative manner. Through his monumental installations and site-specific works, Serra solidified his reputation as an artist who could profoundly alter our understanding of space, material, and the act of viewing art.