Rychlovský hrádek, also known as Hradiště u Dolních Štěpanic, is a vanished castle in the cadastral area of Horní Štěpánice near Benecko. It lies southwest of Štěpanická Lhota and northwest of Horní Štěpánice. Constructed at the end of the 13th century, it served as a defensive structure during early colonization efforts in Bohemia under the Přemyslid dynasty. Despite its historical significance, no written records of Rychlovský hrádek's existence have survived, and it is not documented on Tereziánské or Josefovské maps nor on Graupar's map of Krkonoše from 1765.

The origins of Rychlovský hrádek trace back to the late 13th century when Bohemia was expanding and consolidating territory. The castle likely served as a defensive fortification for the Valdštejn family, who controlled much of the surrounding area, including Dolní Štěpánice. Although no specific ownership records have survived, historical sources suggest that the Valdštejns may have established Rychlovský hrádek to protect their lands during this period of increased colonization.

Architecturally, Rychlovský hrádek was a single-chambered fortification with an irregular shape. Wood was its primary construction material. Defensive elements included a moat and rampart on the northern and eastern sides, while steep slopes provided natural protection to the southern and western perimeters. It is assumed that the entrance was located where the rampart was interrupted in the north, although no specific details about the entrance have been documented.

The Valdštejn family likely owned Rychlovský hrádek during its brief existence, from its construction at the end of the 13th century until its collapse at the beginning of the 14th century. Despite its short lifespan, the castle played a role in territorial defense and noble land consolidation.

Today, Rychlovský hrádek exists only as remnants of fortifications with no surviving buildings or structures identified through archaeological surveys. The site offers insight into early medieval defensive strategies and the challenges historians face due to the lack of written records. While there are no specific monuments within a 5 km radius, the natural landscape around the castle, including steep slopes, provides insight into its strategic location.

Visiting Rychlovský hrádek offers an opportunity to explore Bohemia's medieval past and reflect on the historical significance of such fortifications in regional defense. Although much remains unknown about this vanished castle, it stands as a testament to the era's architectural ingenuity and the enduring mystery of its history.