Crickhowell House was constructed in 1993 to the design of Holder Mathias Alcock, and named after Roger Nicholas Edwards, Baron Crickhowell (1934?2018) who played an important role in the regeneration of Cardiff Bay in the 1980s. The building was the home of the National Assembly from 1999 until 2006, while the current Senedd Building (NPRN 403909), on to which Crickhowell House adjoins, was completed. In 2008, Crickhowell House was renamed Ty Hywel, after King Hywel Dda (d.950). The former debating chamber of the Assembly is now Siamber Hywel, the National Assembly's youth debating chamber and interactive learning centre.

The six-storey office block is laid out on a V-plan and is open to the east. It is largely constructed of orange brick with narrow bands of reconstituted stone at the top of the first storey, at the sill lived and top of the second storey, and the sill level of the third storey. The northern corner is recessed and entirely glazed, culminating in a sharp apex above the roofline, with a railing. A front section of the wings extending to the south east and south west and are stepped down a storey every 4-5 bays to further emphasise this corner. A glazed bridge connects Crickhowell house to the Senedd Building to the south west.

(Sources: Newman, Buildings of Wales: Glamorgan (London: 1995), p. 268; `New Name for Assembly former home?, Wales Online, 3.3.2008)
A.N. Coward, RCAHMW, 31.7.2018